Question

Fill in the blank with a suitable preposition:
I’ll call you _________ seven o’clock.
A. In
B. On
C. At
D. Of

Answer 1

Hint: Prepositions are commonly short words, and they are usually put in front of nouns directly. Typically, it is a function word that combines with a noun phrase to form a phrase that normally communicates a predication or modification.

Complete answer:
 Prepositions are phrases that demonstrate associations with the other phrases in the sentence. Place prepositions are used to refer to a place, usually to indicate something or someone's location.

Prepositions signify direction, time, place, space and other abstract kinds of relationships. Let us look at examples for each. The prepositions are in italics for your convenience.
Direction: Look to the left and you will see our destination.
Time: We have been working since this morning.
Location: We saw a movie at the theater.
Space: The dog hid under the table.

Now, let us take a look at the given question. To denote time in a sentence, prepositions of time are used. Let us look at the use of different choices in the option as a time preposition:
At: It refers to the particular time of day, sometimes used for night.
In: It refers to a time period, usually years / months / seasons / morning / afternoon / evening.
On: It refers to the days / time period.
Of: It is not commonly used as a time preposition, but also used to convey time in relation to the next hour. A specific / exact period of time "seven o'clock" has been stated in the sentence. The necessary preposition here, therefore, is at.

Hence the correct answer is option ‘C’

Note: Prepositions may be confusing at times. Always refer to the preposition’s relation with the noun. It will help you to solve any given question on preposition.