A deficiency of which of the following intermediate cells would result in a marked increase in the clotting time of blood?

A) Lymphoblast
B) Megakaryoblast
C) Monoblast
D) Myeloblast
E) Proerythroblast

Megakaryoblasts are the precursor cells to megakaryocytes, which are responsible for the production of platelets (thrombocytes). Platelets play a crucial role in blood clotting, so a deficiency in megakaryoblasts would lead to a decrease in platelet production and consequently, an increase in clotting time.