In humans red blood cells are primarily produced in the red marrow. to which body system does red marrow belong? a. integumentary system b. circulatory system c. muscular system d. skeletal system

Option D

Explanation:

Bone marrow is an integral part of bones and hence it is a part of skeletal system. It is of two types – a) Red bone marrow and b) yellow bone marrow

a)Red bone marrow which is responsible for producing red and white blood cells

b)Yellow bone marrow which is also responsible for producing white blood cells  

The red marrows are mainly found in bones like  

a)Breast bone

b)Rib bones

c)Skull bones

d)Hip bone  

e)At the femur and humerus ends of long bones  

Hence, option D is correct

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.