Answer:
Convenience sampling.
Explanation:
We are asked to identify the sampling method of given choices, which is most likely biased.
first of all we will see how these samples are taken one by one.
Cluster sampling: In this sampling researcher divides population in different groups. Then a simple random sample of clusters is selected from the population. The overall sample consists of every member from some of the groups.
Systematic sampling: In this sampling method sample members are selected from a large population by putting them in some order. A starting point is selected at random, and every nth member is selected to be in the sample. As in a population of 10,000 people, a statistician might select every 50th person for sampling.
Simple random sampling: In this sampling method every member and set of members has an equal chance of being included in the sample. As choosing the names of 15 members of a company from a bowl.
Stratified sampling: In this method population is split into different groups. The overall sample consists of few members from every group. The members are chosen randomly from each group. This method guarantees that members of all groups will be represented in the sample.
Convenience sampling: In this method samples are taken from the people who are easy to reach. The researcher chooses a sample that is readily available in some non-random way. This method is biased because the sample is not representative of the entire population.
Therefore, convenience sampling is most likely to be biased.