Assertion (A) is correct because the sentence "The details of the incident" was not known” is grammatically incorrect due to subject-verb agreement. "Details" is plural, so the verb should be "were" instead of "was".
Reason (R) is also true. In constructions like "Noun + Preposition + Noun,” the verb agrees with the noun before the preposition (here, "details"), which is plural. Therefore, Reason (R) correctly explains why the sentence is grammatically incorrect.
Study the following sentence:
The statue of Christ the Redeemer is located on Rio de Janeiro, the largest city of Brazil. (Which of the following parts of the sentence is grammatically incorrect?)
Which of the following statements correctly explains the use of articles in the following sentence?
After earning an MBA, Srinivas was able to approach a mathematical problem from both a business and analytical perspective.