Answer:
a) will fall
Step-by-step explanation:
Option a) "will fall" is the correct answer because it is a future tense verb that indicates a future event, in this case, falling down.
Option b) "are falling" is incorrect because it is a present tense verb that expresses a continuous action, which is not applicable in this context.
Option c) "re going to fall" is also incorrect because it is a present tense verb with the auxiliary verb "going", which expresses a future event. However, "going to fall" is not an appropriate expression in this context.