Explanation

Shab-e-Qadar is widely considered the most important night in Ramadan due to its immense spiritual rewards. Shab-e-Bara'at refers to a different significant night, not specifically the most important one of Ramadan. Shab-e-Miraj relates to the Prophet's ascension and is not designated as the most important night of Ramadan. None of these is incorrect because A is the established answer.