"
Nimble" means quick and light in movement, like a skilled dancer or an athlete.
Let us check each option:
Giant refers to a mythical being that is huge in size and strength; it is not the opposite of nimble.
Clumsy describes someone who moves awkwardly or struggles to handle things smoothly.
Quick means moving fast or finishing something in a short time, which is similar in meaning to nimble, not opposite to it.
Frank means open, honest, and direct, even when the truth is hard to hear; it has no relation to nimble.
Since nimble means moving easily and gracefully, its antonym is
clumsy, which means moving awkwardly.
Therefore, the correct answer is
clumsy.