A number is an abstraction ………………. no physical existence.
(B) that has
(C) to have
(D) which it has
This is the question on the use of the correct subject and predicate.
The choice (A) will give the version:
A number is an abstraction has no physical existence.
This sentence has two verbs, but without a connecting conjunction.
So, this choice (A) is a wrong one.
(B) completes the sentence by making it a grammatically correct and meaningful one.
A number is an abstraction that has no physical existence.
(C) makes the sentence a grammatically correct one but the sentence is meaningless one.
A number is an abstraction to have no physical existence.
The choice (D) gives the version:
A number is an abstraction which it has no physical existence.
This sentence has unnecessary pronoun it, so it is a wrong one.
So, (D) is also wrong.
So, we can choose (B) as the answer.
TOEFL : Model Questions Index