Question

Fill in the blanks with the appropriate option:
He ________ weak must build his strength.
a) who is
b) which is
c) who are
d) whom are

Answer 1

Hint: The sentence suggests that the person talking is specifying who he is talking about to someone. When specifying about a person, a specific ‘wh-’ word is to be used.

Complete answer:
The sentence is structured in such a way that the meaning inferred becomes that the person is specifying exactly which person is weak and telling them to build their strength.
In English grammar, a "wh- word" is one of the function words used to begin a wh- question-
what, who, whom, whose, which, when, where, why, and how. Wh- words can appear in both direct questions and indirect questions, and they are used to begin wh- clauses.

Now we know what we are looking for. Let’s look at our options one by one-
a) who is - This word is correct as the word ‘who’ is used to refer to a person. The verb in the phrase is also correct, as the subject ‘he’ is singular. This is the required answer. So, this is the correct option.
b) which is - The word ‘which’ is usually used to refer to a person. The verb in the phrase is correct, but the whole phrase is wrong for the given sentence. This is not the required answer. So, this is an incorrect option.
c) who are - This word is correct as the word ‘who’ is used to refer to a person. However, the verb used is plural and it is wrong to use a plural verb for a singular subject. This is not the required answer. So, this is an incorrect option.
d) whom are - This phrase is grammatically incorrect. It cannot be used in the given sentence. This is not the required answer. So, this is an incorrect option.

Note:
 Identify the structure of the sentence, and the parts of speech used. They are in a particular order. Now, use the trial and error method and see which option best fits into the sentence.