The proverb, 'Prevention is better than cure' means: 'It is easier to stop something happening in the first place than to repair the damage after it has happened'. Hence, the word which can complete the proverb meaningfully is 'cure' given in option C.
The other words, 'invention', 'imagination' and 'creation' do not complete the proverb meaningfully. Hence, options A. B and D are incorrect.