The word "commodious" means spacious and comfortable, especially in reference to rooms or accommodations.
Its antonym should convey the opposite — something that is not spacious or comfortable.
Let’s evaluate the options:
(A) Convenient – Related to ease or practicality, not space.
(B) Roomy – A synonym, not an antonym.
(C) Uncomfortable – Correct; it is the opposite of comfortable and spacious.
(D) Comfortable – A direct synonym of commodious.