21.
The answer is: B
Explanation
The correct option is B: 3.
As per the rule 3 of The Advocates (Right to Take up Law Teaching) Rules, 1979, an advocate may, while practising, take up teaching of law in any educational institution which is affiliated to a University, so long as the hours during which he is so engaged in the teaching of law do not exceed three hours in a day. This rule was made under the Advocates Act, 1961, which regulates the legal profession in India. The rule is intended to allow advocates to pursue law teaching as a part-time employment without affecting their practice.