In this English grammar sentence improvement question, you are given a future time expression and must choose the option that best completes the sentence "My parents ______ Delhi by Monday next" in standard, natural English. Select the option that gives the most appropriate future tense form.

Introduction / Context:
This question tests correct usage of English future tenses, especially the future perfect tense with a time expression introduced by the preposition "by". Competitive exams frequently check whether candidates can distinguish between simple future, progressive, and future perfect forms in sentences describing an action that will be completed before a specific future point in time.

Given Data / Assumptions:

• Sentence frame: My parents ______ Delhi by Monday next.
• The meaning suggests that a journey will be completed before or not later than "Monday next".
• We must choose from several tense forms of the verb phrase.
• The context is a prediction about a completed future event.

Concept / Approach:
When we talk about an action that will already be finished before a specified time in the future, English uses the future perfect tense "will have + past participle". The phrase "by Monday next" signals a deadline in the future, so the correct grammatical choice is "will have reached". Simple future "will reach" is also possible in casual speech, but examinations often expect the precise future perfect form when "by" plus a future time point is used.

Step-by-Step Solution:
Identify the future point in time: "Monday next".Notice that the action (reaching Delhi) is expected to be completed before or not later than that day.Recall the structure of the future perfect tense: will have + past participle.Apply this pattern to the verb "reach": will have reached.Insert it into the sentence: "My parents will have reached Delhi by Monday next."

Verification / Alternative check:
Read the complete sentence: "My parents will have reached Delhi by Monday next." It clearly states that at some time before or by Monday, the journey will already be over. This fits the common pattern of future perfect usage found in grammar references and matches the meaning suggested by the preposition "by".

Why Other Options Are Wrong:
Option A: "are reaching" uses the present continuous and is incorrect with the future deadline "by Monday next" in this neutral statement. Option C: "were reaching" is a past continuous form and does not match the future reference. Option D: "No improvement" keeps "will reach", which is not the best tense with "by Monday next" from an examination perspective, because it does not emphasize completedness as clearly as "will have reached".

Common Pitfalls:
Learners often use simple future with every future time expression and ignore the special meaning of "by". They may also confuse present continuous used for planned future actions with the more precise future perfect used for completion before a deadline. Remember that future perfect is preferred when you want to highlight that something will already be finished before a specific point in future time.

Final Answer:
The correct improvement is will have reached, giving the sentence "My parents will have reached Delhi by Monday next."