AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
Option A is correct.
Both A and R are true and R is the correct explanation of A. Metallic oxides are called basic oxides because they react with acids to form salt and water, just like a base does, which justifies their basic nature.
The textbook (Chapter 3) states that "metals combine with oxygen to form basic oxides." The reason correctly explains why they are called basic — their acid-neutralising behaviour mirrors that of bases. Since R directly and logically explains A, option A is the right choice. Avoid choosing B here; R is not merely a coincidental true statement — it is the actual basis for the assertion.