Identify non-probability samples from the following:
A. Simple random sample
B. Quota sample
C. Systematic sample
D. Snowball sample
Choose the correct answer from the options given below:

Correct option is D

In sampling techniques, non-probability sampling methods do not give all the individuals in the population equal chances of being selected. Instead, these methods rely on subjective judgement, convenience, or other non-random processes. Let's analyze the options:
A. Simple random sample: This is a probability sampling method where each member of the population has an equal chance of being selected.
B. Quota sample: This is a non-probability sampling method where the researcher selects individuals to meet a specific quota or characteristic, based on demographic or other relevant criteria, without giving each member of the population an equal chance of being selected.
C. Systematic sample: Although systematic sampling involves a systematic approach to selection (e.g., every nth individual is selected), it starts from a random point. It is considered a probability sampling method, despite its systematic approach.
D. Snowball sample: This is a non-probability sampling method often used in qualitative research where existing study subjects recruit future subjects from among their acquaintances. This method is particularly useful for accessing hard-to-reach or specialized populations but does not give every individual an equal chance of being selected.
Given this, the non-probability samples from the options provided are B (Quota sample) and D (Snowball sample), making the correct answer (d) B and D only.