The correct answer would be;
¿A ti te preocupa no saber qué estudiar?
The correct answer is: "Es preciso que uses sombrero"
In english (if needed): Pamela: "How can I protect my face from sunburn?" Roberto: "It's necessary to wear a hat."
Hoped I helped ^.^
The correct answer is B.
option A is for "Ellos" (they)
option C is for "yo" (I)
option D is for a third person but the conjugation works for "us." just try to translate the whole sentence: "The teacher gives us the books to the students." it does not make sense.
However, if we use "B" the sentence is written properly. "La profesora les da los libros a los estudiantes" The teacher gives the books to the students.