What is the singular version of criteria, and why is it irregular? A.

Criterion is the singular version, and it is irregular because it is a Greek word in which the –on is changed to –a in its plural form.

B.

Criteris is the singular version, and it is irregular because it is a Greek word in which the –is is changed to –a in its plural form.

C.

Criterium is the singular version, and it is irregular because it is a Greek word in which the –um is changed to –a in its plural form.

D.

Criterion is the singular version, and it is irregular because it is a Latin word in which the –on is changed to –a in its plural form.