All you have to do to answer the questions is use the "tú" form of the infinitives. For -AR verbs this is "-as," for -ER verbs, "es," and -IR verbs it's, "-es."
So you just have to drop the -ar, -ir, -er, ending and as -as or -es:
¡Tú estudias mucho!
¡Tú comes la comida saludable!
¡Tú eres cortés! Es importante tener modales. (Also, "ser" is irregular to that's why the answer here is eres.)
¡Tú haces ejercicio todos los días!
¡Tú dices la verdad!
Hope this helps!