Correct Answer:
B. 45 years
The correct answer is 45 years. According to Article 41(1) of the Constitution of Pakistan, a person is qualified to be elected as President if they are a Muslim, not less than forty-five years of age, and qualified to be elected as a member of the National Assembly. This age requirement ensures that the individual holding the highest office has sufficient experience and maturity.
The other age options, 40 years, 50 years, and 55 years, are incorrect as they do not align with the specific constitutional provision for the minimum age qualification for the President of Pakistan.