In most stable freshwater environments, populations of daphnia are almost entirely female and reproduce asexually. however, males are observed in low oxygen environments or when food is scarce. based on these observations, a researcher suggests that male daphnia develop in response to unfavorable environmental conditions. this is an example of a:

Cancer cells spread to other parts of the body by entering the bloodstream. which of the following organs could prevent a cancer cell in the bloodstream from spreading, and why? a. the spleen, because it releases lymphocytes into the blood b. the peyer's patches, because they release lymphocytes into the blood c. the lymph nodes, because they release lymph into the blood d. the thymus, because it releases lymph into the blood