Consider a relation schema R = (U, V, W, X, Y, Z), on which the following functional dependencies hold:
{U → V, VW, → X, Y → W; X→U}
The candidate keys of R are:

Correct option is D

To determine candidate keys, we need to find minimal sets of attributes that can uniquely identify all attributes in the relation schema.
Information Booster:
Identifying Candidate Keys:
· Start with the dependencies and apply closure analysis to find all attributes derivable from certain sets.
· Using the dependencies given, derive that UYZ, VYZ, and XYZ can serve as minimal superkeys, making them candidate keys for the schema.
Additional Knowledge:
Other combinations do not cover all attributes without violating minimality, making them invalid candidate keys.