When sampling is done, it is possible to intervene as little as possible in the choice of the objects of study so as not to affect the results obtained from the research process, where it is often sought to know how the study population is distributed.
In that order of ideas, sampling errors are usually related to the choice or size of the sample, either because the amount of data is inappropriate or because in the selection process a bias occurred that modifies the chances of a individual, or class of individuals, be included in the sample.
In this case, both the choice of the individuals and the randomness with which they were chosen give basis to affirm that the data is not biased.
Answer
b) It appears to be sound because the data are not biased in any way. Your answer is correct