Find the synonym of the underlined word.
 In ancient primitive cultures, a person who touched a forbidden object would suffer grave injury.
A. Unexpected
B. Frequent
C. Critical
D. Explosive
E. Sufficient

Hint: In this question we need to look for the synonym of the given word ‘grave’. Let us first understand what synonyms mean – Two words with a nearly common meaning or same meaning words are called synonyms.

Complete answer:
 The word grave means: bad, sad, serious injury, critical, etc.
Now let’s examine and understand the given option above.
> Unexpected: the word unexpected means: something that can’t be expected, surprising, astonished, etc. As this word has different meaning so it can’t be an appropriate option.
Synonym: unanticipated, unpredicted, etc.
> Frequent: the word frequent means: something that happens often, or to go to any place often, etc. As this word has different meaning that is not even related so it can’t be an appropriate option.
Synonym: repeated, periodic, recurrent, etc.
> Explosive: the word explosive means: having dangerous effects, explosion, a violent expansion, bursting with noise, etc. As this word also has different meaning so it can’t be an appropriate option.
Synonym: flammable, volatile, volcanic, bomb, etc.
> Sufficient: the word sufficient means: enough, availability of something, as much as is necessary, etc. So this word has completely different meaning and it can’t be an appropriate answer for the given question.
Synonym: plenty of, ample, adequate, etc.
> Critical: Here the word critical has the same meaning “bad, sad, serious injury, censorious, condemnatory, etc”. As it is related and defines the sentence in the most appropriate way, so the suitable synonym will be option [C] Critical.

So, the correct answer is option C.

Note: Studying of different vocabulary words is necessary.
Try to identify the meaning of the word and evaluate whether it has a positive negative or neutral connotation.