Which sampling could be effective during a sampling frame is difficult to identify in research?

Correct option is D

Ans. (d)
Sol. Snowball sampling is used when the population is hard to locate or hidden. One participant refers another.
Explanation of each option:
· (a) Quota – Ensures representation but requires predefined categories.
· (b) Convenient – Easiest but may be biased, not ideal when frame is unknown.
· (c) Purposive – Based on judgment, but still needs frame knowledge.
· (d) Snowball – Correct answer. Ideal when the sample frame is not clear (e.g., drug users, rare populations).