Answer: d. Random
Explanation:
In statistics, a simple random sampling is a sampling technique in which a subset of the population named as sample is drawn by the researcher in such a way that all the individuals have equal probability of getting selected.
If the Total population size is N , then the probability for any individual of getting selected is
.
Therefore , the sampling designs do all members of a population have an equal chance of being selected is random sampling.
Rest of other sampling methods does not give equal chance to the members of the population of getting selected.