The correct option is A To predict a future event
The tense of a sentence denotes a time, whether it is the time now (present), time then (past) or the time to come (future). The verb of a sentence has most to do with the tense. The simple future tense refers to an action that is about to take place, or will take place in the time to come, it predicts a future event, for example, 'I will go to school tomorrow', hence option A is correct. Option C is the function of the simple present tense, it refers to a general truth or a habit or routine, for example, 'I go to school everyday', hence option B is incorrect. Option C is the function of the present continuous tense, it refers to an action that is going on at the moment, 'I am going to school', hence option C is incorrect. Option D is the function of the present perfect tense, it refers to an action that began in the past and completed close to the present time, 'I have reached school', hence option D is incorrect.