Assertion: Yellow bone-marrow is reserve erythropoietictissue.

Reason: After severe bleeding yellow marrow may convert to red marrow.

Kindly answer sir/mam.

Both Assertion and Reason are true. Yellow bone marrow is incapable of erythropoiesis and also during severe blood loss, the body can convert the yellow bone marrow back to red bone marrow so that the blood cell production increases.