The most appropriate option which exhibits the same logical relationship as conductor : orchestra is director : cast.
The conductors is a person who takes charge of the performance and display of singers or orchestras as they sing using gestures to give rules and guidelines to follow in terms of notes and tempos to performing artists. Similarly, the relationship is synonymous between directoe and casts, as the director gives guidelines to artists and assign roles during the making of a film.
Though other options shows relationships between one another, however, the relationship between these selected option is based specifically on one party conducting the actions and performance of the other.
A. A has both genders of the students and since we don’t know the amount of students of either gender, this serves as an indication that not all the students are of one gender or another.