In Spanish, we use los mandatos to talk about commands. So, the informal commands are also called the informal imperative. For the informal commands we use tú as the singular form. In this way, we use this type of commands to tell a friend, a pet, a family member, a child, a classmate, a partner, among other, to do something. This problem stands for the affirmative form. So, for the affirmative form, the conjugation of the verb we use is the third-person singular in the present simple. The verb is hablar and the correct conjugation is habla.
So, the right answer is: Habla
