Choose the correct alternative which will improve the part of the sentence given in quotes.
After a 'period for imprisonment' she renounced terrorism.

Correct option is A

The correct substitution of the quoted words is "period of imprisonment".
Explanation: The phrase "period for imprisonment" is incorrect as it improperly uses "for" which suggests purpose rather than composition or connection. "Period of imprisonment" correctly denotes a duration characterized by imprisonment.
Grammatical rule used: The preposition "of" is used to indicate belonging or association between a noun and its qualifier.
Example: He served a period of six months in imprisonment.