Replace the word in the bracket from the set of options given: You should work hard (in) weekends.

Correct option is C

The correct preposition to use with "weekends" in this context is "during." "During weekends" implies the period of time when the action (working hard) takes place. "During" is appropriate when referring to a span of time in which something occurs. Hence, "You should work hard during weekends" is grammatically and semantically correct.
Explanation of options: (a) from – This implies a starting point and usually needs an endpoint ("from...to"), which does not fit the sentence. "From weekends" is grammatically awkward and doesn’t convey a clear meaning here.
(b) at – "At weekends" is sometimes used in British English, but it is less standard than "on weekends" or "during weekends" in general usage. Still, it doesn’t suit the structure of the verb phrase "work hard" naturally in this context.
(c) during – This is the correct choice. It shows that the action of working hard occurs in the time frame of the weekends. It fits naturally and accurately within the sentence.
(d) with – This would suggest an instrument or accompaniment and is not suitable for referring to a time period. "With weekends" makes no grammatical or logical sense in the given context.