Answer:
Los perros le solestan a mi hermano
Step-by-step explanation:
I realize you put an "s" instead of "m" for a bad word reference here. Now, let me explain to you this and discart all the options instead of just giving you the answer.
The question is: Qué le solesta a tu hermano?. In english, What's bother your brother?
Option a. Los perros me solestan. English: The dogs bothers me.
This clearly is not the correct choice, because the answer makes reference to yourself, and the question is a reference to your brother, so, it's not the correct choice.
Option c. Los perros me solestan a mi hermano. English: The dogs are bothering my brother.
This could be the correct choice, however, in spanish, you are using "me" in addition to "solestan", this means you are using first person too, making a reference to yourself, and not neccesary your brother.
Option d. Los perros solestan a mi hermano. English. Dogs bother my brother
In this case, it could also be the correct choice, however, in this case, it's making a reference to the present time and action, staying that the dogs are actually bothering your brother now, and it's not something that is an general behavior or inquiry of your brother. This can be noted better in spanish rather than english.
Option b. Los perros le solestan a mi hermano. English: Dogs bother my brother.
Again, in english is the same as before, but in this case, in the question and in the answer, we use the pronoun "le", stating that the dogs, just for the simple fact that they are dogs, bothers directly your brother. Therefore, this is the correct choice.