The Research Team Established Similar Lymphocyte Cultures from a Number

The research team established similar lymphocyte cultures from a number of human donors, including healthy teenagers of both genders, patients already suffering from long-term bacterial infections, and elderly volunteers. They found that the increase in lymphocyte incorporation after pathogen introduction was slightly lower in some of the women teenagers and significantly lower in each of the elderly persons. They repeated the study with a larger number of samples but got the same results. What might be among their conclusions?

A) The young women showed these results because they have poorer nutrition.
B) The elderly persons' samples demonstrated their lowered immune responses.
C) The young men had higher response because they are generally healthier.
D) The patient samples should have had the lowest response but did not, so the experiment is invalid.
E) The elderly donor samples represent cells no longer capable of any cell division.