The correct answer is A. Hay un profesor con el estudiante.
The sentence says - There is A professor with THE student. In Spanish, the article A is either UN or UNA (depending on the gender) for singular, and UNOS and UNAS for plural. The article THE is either EL or LA, depending on the gender.
No te entiendo pero - caerse, caerte y callo
Its A because it is feminine
Ningunas fruta is correct.
