Select the most appropriate option to fill in blank No.10
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. of.
Of usually shows a connection or belonging.
We use 'for' with a period of time in the past, present or future. We use 'since' with a point in time in the past. For refers to periods of time, e.g. 3 years, 4 hours, ages, a long time, months, years.
Ex:- They've lived in Oxford since 2004.
Therefore the sentence will become:- The change in timings will be effective for a period of 3 years.