When investigating the effect of co-culturing nk cells with eosinophils for up to 12 hours, researchers chose to co-culture all samples in the presence of interleukin-5, a cytokine.
what is the most likely reason for this decision?

a. interleukin-5 facilitates degranulation in nk cells.
b. interleukin-5 inhibits the cytotoxic effects that nk cells have against eosinophils.
c. eosinophils die rapidly when not exposed to interleukin-5.
d. the researchers were directly testing the effect of interleukin-5 on eosinophil activity.