Which one of the following is known as non-probability sampling?

Quota sampling is a non-probability method, filling fixed quotas by the interviewer's choice rather than by chance.

Members are picked to meet subgroup targets without known selection probabilities.

Cluster sampling divides the population into clusters chosen at random and is a probability method.

Systematic sampling selects every kth unit from a random start and is also probability based.

Stratified random sampling draws random samples within strata and remains a probability method.

Non-probability methods trade representativeness for speed, low cost and convenience.