In the following sentence, the blank must be filled with a suitable preposition. Select the correct alternative: "Providence smiles ______ those who are diligent."

Introduction / Context:
This question checks your understanding of standard English prepositional phrases, especially set expressions used in a slightly formal or literary style. The sentence mentions "Providence", a word often used to describe divine care or fate, and asks which preposition completes the idiomatic collocation "smiles ______ those". Correct preposition choice is crucial for sounding natural and accurate in English.

Given Data / Assumptions:

• The sentence is: "Providence smiles ______ those who are diligent."
• We must choose the preposition that fits best in formal English.
• Options: with, in, upon, over.
• We assume "Providence" refers to divine guidance or fate favouring people.

Concept / Approach:
English has several fixed phrases combining "smile" with a preposition: "smile at someone", "fortune smiles upon someone", etc. When we speak about fate or fortune being favourable to a person, the standard expression is "fortune smiles on/upon someone". Since "Providence" is used here much like "fortune", we should recall the idiomatic phrase "smiles upon". The approach is to rely on familiarity with these set expressions rather than literally trying to insert any preposition that seems possible.

Step-by-Step Solution:
Step 1: Understand the meaning: the sentence states that divine favour (Providence) favours or blesses people who are diligent. Step 2: Recall the idiom "fortune smiles upon the brave" or "fortune smiles on those who take risks". Step 3: Test "with": "Providence smiles with those who are diligent" is not a recognised phrase and sounds unnatural. Step 4: Test "in": "Providence smiles in those who are diligent" is grammatically odd and does not express favour. Step 5: Test "upon": "Providence smiles upon those who are diligent" matches the well known literary pattern and sounds correct. Step 6: Test "over": "Providence smiles over those who are diligent" is not a standard collocation. Step 7: Conclude that "upon" is the correct preposition here.

Verification / Alternative check:
You can verify by comparing other similar expressions: "Destiny smiled upon him", "Luck smiled upon the team at the last moment." Dictionaries often list examples like "fortune smiles on/upon someone" to indicate that good luck or favourable circumstances come to them. Substituting Providence for fortune does not change the preposition; "upon" remains the natural choice in formal English.

Why Other Options Are Wrong:

• with: We say "smile with joy" when describing how someone smiles, not "smiles with those" when describing favour.
• in: "Smile in someone" does not make sense in this context; it would require a completely different structure.
• over: While "rejoice over" or "weep over" are common, "smile over someone" as an idiom for bestowing favour is not standard English.

Common Pitfalls:
A common mistake is to overgeneralise from phrases like "laugh at" or "smile at" and assume that any preposition will do. In idiomatic English, many phrases have a fixed form that must be learned as a whole. When the subject is an abstract concept like fortune, luck, or Providence, the phrase "smiles upon" or "smiles on" is strongly preferred and widely used in literature and formal writing.

Final Answer:
The correct completion is "Providence smiles upon those who are diligent."