Ex.:
Cantar
Ustedes cantan.
Regular ending is -an.
I would say A because if she is suprised that he only says dear than it would more than have to be A
Yo hago mi tarea todos Los dias.
The conjugation is because it's "I". In Spanish when there is an "I"/ "yo", "o" usually is the proper form to use.
Answer:
A= las cascadas
Explanation:
las cascadas are waterfalls.
The sentence basically talks about someone being scared when they saw
[ blank ] of water going down the river. The only one that can make sense is waterfalls. So it is A.