The question is saying to choose the correct option for an informal command. 
 - A) Talk to your sister [habla = talk in command form] = present
 - B) I talked with your brother [hable = I spoke] = past tense
 - C) They talk to your sister [hablan = they talk] = plural present
 - D) You talk with your brother [hablas = you are talking] = present
The correct answer is A, since it is a command.