There are two statements marked as Assertion (A) and Reason (R). Mark your answer as per the options given below.

Assertion: Bipolar I disorder involves both mania and depression, which are alternately present and sometimes interrupted by periods of normal mood.
Reasoning: Bipolar mood disorders were earlier referred to as manic-depressive disorders.

Both Assertion (A) and reasoning (R) are correct but R is not the correct explanation of A.

The correct answer is Option 2: Both Assertion (A) and reasoning (R) are correct but R is not the correct explanation of A.

Assertion: Bipolar I disorder involves both mania and depression, which are alternately present and sometimes interrupted by periods of normal mood. Correct — Bipolar I disorder involves both mania and depression, which are alternately present and sometimes interrupted by periods of normal mood.
Reasoning: Bipolar mood disorders were earlier referred to as manic-depressive disorders. Correct — The term "manic-depressive illness" was historically used to describe what is now known as bipolar disorder.

However, while both statements are factually correct, the Reason (R) is not the explanation for the Assertion (A). The assertion explains the clinical features of Bipolar I disorder, while the reason talks about its historical terminology.