If the following sentence were put into standard form as a categorical proposition, what would the copula be? Everyone in my office can keep a secret.

A) are
B) are not
C) is
D) is not
E) can

The copula in a standard form categorical proposition connects the subject to the predicate, typically using a form of "to be" such as "are" or "is." In this sentence, converting it to standard form would involve stating something like "All people in my office are secret-keepers," making "are" the correct copula.