In this sentence-improvement question on prepositional phrases, decide which phrase, if any, should replace the highlighted part "one puts in to the professional front" in the sentence "My father told me that all the labor and effort one puts in to the professional front is meant to make life easier and therefore any professional success coming at the cost of personal happiness is pointless."

Introduction / Context:
This question checks whether you can judge if a complex prepositional phrase in a sentence really needs correction. The sentence reads: "My father told me that all the labor and effort one puts in to the professional front is meant to make life easier and therefore any professional success coming at the cost of personal happiness is pointless." The highlighted phrase is "one puts in to the professional front". You must decide whether one of the suggested alternatives improves the grammar and meaning, or whether the original phrase is acceptable as it is.

Given Data / Assumptions:

• Original phrase: "one puts in to the professional front".
• Option (i): one puts at the professional front is meant to make life.
• Option (ii): one puts onto the professional front is meant to make life.
• Option (iii): one who puts into the professional front is meant to make life.
• The intended meaning is that labour and effort that a person invests in their professional life is meant to make life easier.

Concept / Approach:
In the phrase "the labor and effort one puts in", the phrasal verb "put in" is natural and correct in English. It means "to invest" or "to devote time and effort". The additional phrase "to the professional front" further specifies where that effort is invested. While the wording is somewhat formal or slightly unusual, it is still grammatically acceptable: "to the professional front" can be understood as "in the area of one's professional life". The key is to check whether any suggested alternative gives a clearer and more idiomatic expression without introducing new errors. As we shall see, all three alternatives actually damage the grammar or the sense.

Step-by-Step Solution:
Step 1: Read the original: "labor and effort one puts in to the professional front". Step 2: Recognize "puts in" as a correct phrasal verb meaning "invests" or "devotes". Step 3: Understand that "to the professional front" means "towards the professional side of life", which is conceptually acceptable, even if slightly formal. Step 4: Examine option (i): "one puts at the professional front" – here "puts at" is not idiomatic; we normally say "puts in" or "invests in". Step 5: Examine option (ii): "one puts onto the professional front" – "puts onto" is also awkward and unidiomatic in this context. Step 6: Examine option (iii): "one who puts into the professional front" – this changes the structure and creates a mismatch between subject and verb ("one who puts ... is meant to make life" is unclear). Step 7: Conclude that the original phrase, although formal, is grammatically acceptable and better than the proposed alternatives.

Verification / Alternative check:
We can paraphrase the sentence as: "My father told me that all the labor and effort one puts in at the professional front is meant to make life easier." This confirms that "puts in" is the key phrasal verb and that adding a preposition like "at" or "on" in the alternatives does not truly improve clarity. Since the exam offers only the slightly awkward alternatives and not a nicely polished option such as "puts into his or her professional life", it is reasonable to treat the original as acceptable and to choose "No correction required".

Why Other Options Are Wrong:
Option (i) uses "puts at", which is not idiomatic for describing invested labor or effort. Option (ii) uses "puts onto", which again is unnatural in this context and does not match standard usage. Option (iii) changes the structure to "one who puts into the professional front", which breaks the original grammatical balance and confuses the subject of the verb "is meant".

Common Pitfalls:
Many students assume that a long or slightly formal phrase must be wrong just because simpler language exists. However, in sentence-improvement questions, you are not free to rewrite the entire sentence; you may only choose among the given options. If none of the alternatives are free from errors and truly better, you must confidently choose "No correction required". Always check each suggested replacement carefully for grammar and meaning rather than changing the sentence automatically.

Final Answer:
The original phrase is acceptable, so the correct choice is No correction required.