Final answer:
Thrombocytopenia is the likely cause of the decreased platelet production in the chemo client with low platelet aggregation.
Step-by-step explanation:
The likely cause of the decreased platelet production in the chemo client with low platelet aggregation is B. Thrombocytopenia. Thrombocytopenia refers to a condition where there is a low platelet count in the blood, which can be caused by various factors including chemotherapy. When platelet production is decreased, it impairs the ability of blood to form clots, leading to excessive bleeding.