Antonyms and the odd word
An antonym is the opposite. The trap is a synonym sitting in the list. Rigid looks a lot like stiff, solid, and hard. Only flexible goes the other way.
Some items never say “opposite.” They say which word does not belong. Three words share a meaning and one is the odd one out, often the antonym. Raise, lift, and hoist belong together. Drop does not.
Read the stem for does not, opposite, or not belong before you look at the choices.
Worked example
Which word does not belong: raise, lift, hoist, drop?
Drop. The other three move something up.