Step 1: Understanding the Question.
Under the Dissolution of Muslim Marriage Act, 1939, a Muslim wife can sue for divorce if her husband has been insane for a period of 2 years or more.
Step 2: Analysis of Options.
- (A) 1 year: This is incorrect, as the period required is 2 years.
- (B) 2 years: This is the correct answer, as the husband must have been insane for at least 2 years.
- (C) 5 years: This is incorrect, as the period is shorter (2 years).
- (D) 7 years: This is incorrect, as the period is shorter (2 years).
Step 3: Conclusion.
Thus, the correct answer is (B) 2 years.