Explanation
Correct Answer: (b) made
Detailed Explanation
This question tests your understanding of collocations (words that naturally fit together or are traditionally paired by native speakers) and the Present Perfect Tense.
The Collocation Rule: In English grammar, the noun "mistake" does not pair with the verb "do". We do not say do a mistake. Instead, it sets a fixed phrase pattern with the verb "make":
To commit an error⟹make+a mistake
The Tense Rule: The sentence uses the auxiliary helping verb "has", indicating a Present Perfect structural format:
Subject+has/have+V3 (Past Participle form)+Object
Applying both rules together, we must choose the V3 form of "make", which is made.
Therefore, the complete grammatically correct sentence is: "He has made mistakes in the report."