Choose the word which best expresses the opposite of the given word:
Flimsy

a) Frail

b) Filthy

c) Firm

d) Flippant

Hint: Meaning of Flimsy is something that can be easily damaged. The opposite of this word should mean sturdy/strongly or solidly built.

Complete Solution:
Option a ‘Frail’ is an adjective given to someone who is weak or delicate. The word resembles the synonym of the given word ‘Flimsy’ and has similar meaning. The question demands the antonym of the given word. So, option a is not the correct option.
Option b ‘Filthy’ is an adjective. It is a term given to someone or something that is extremely disgusting or dirty. The word has no relation or connection with either the meaning of Flimsy or with its antonym. So, option b is also incorrect.
Option c ‘Firm’ is an adjective. The word expresses the sense of sturdiness or resistance. The meaning is sufficient to indicate that it means exactly the opposite of the given word ‘Flimsy’. It is an antonym of Flimsy. So, this option clearly satisfies the demand of the question and hence is the correct option.
Option d ‘Flippant’ is an adjective which means to have a disrespectful attitude. The meaning has no conformity with the meaning or antonym of Flimsy. So, option d is also incorrect.

Note: The meaning of the word give and the option should be clear to mark out the synonyms or the antonyms.