Is it permissible for me to exercise Ijtihad in religion, or must I follow the opinion of a specific Imam, and is Ijtihad exclusive to the four Imams only, and is maleness a prerequisite for it?

People are divided into three categories: a knowledgeable Mujtahid (independent jurist), a distinguished طالب علم (student of knowledge), and an 'Aami (layperson). The Mujtahid is qualified for Ijtihad, and the student of knowledge distinguishes between the sayings of scholars and acts upon the most preponderant opinion. As for the layperson, they follow (taqlid) whoever they trust among the people of knowledge, as Allah Almighty says: ﴿So ask the people of the Reminder if you do not know.﴾ [An-Nahl: 43]. If a woman reaches the rank of Ijtihad and is qualified for it, she becomes one of the Mujtahids. Scholars are human beings; they err and they are correct, and they are rewarded in both cases. They must be honored and respected because they are the inheritors of the prophets, as the Prophet (peace and blessings of Allah be upon him) said: "He is not from us who does not respect our elders, show mercy to our youngsters, and acknowledge the right of our scholar."