The answer you are looking for is existentialism. Very popular during the Depression and going into the Second World War.
The correct answer is a) Dr. Wong could publish his data in a scientific journal and have different investigators try to reproduce his results. This is due to external validity, when data from a research can be confirm and reproduced, after selecting a proper sample size and determine alfa and beta power, for the study. If no bias exists, other researchers should be able to replicate and validate Dr’s Wong Results.
B and C options are both unacceptable due to ethical issues, and D is incorrect based on the central limit theorem; if Dr’s Wong sample is at least 30 in number (for each group: A=test group and B=control group) the statistical inferences can be translated into larger populations. Smaller samples than this, are not recommended due to bias and internal validity.
Skeptical is the answer to that
This is what I found... Around 75% of farmers reported on spending 10 hours or more a day for harvesting farm work.