Which is not the function of bones?
A.Protection of vital organs
B.Haemopoiesis
C.Muscle attachment
D.Secretion of hormones

Hint:Bones are considered to be the strongest part of the human body. The human body in the infant stage has around 300 bones some of which fuse to become 206 bones during adults.

Complete answer:Bone is divided into two types-
The axial skeleton includes 80 bones. The skull, vertebrae, sternum, and ribs are parts of the axial skeleton. The skull again is divided into two parts-
Cranial:8 bones and provide protection to the brain.
Facial:14 bones and forms the frontal part of the skull.
The appendicular skeleton includes 60 bones in total, that is, 30 bones in each limb forming the humorous, ulna, radius, carpals, metacarpals, tarsals, metatarsals.
Here is the explanation of the above options:
Option A- bones provide protection to vital organs by forming a protective layer around them. So, it is a function of bone.
Option B- Haemopoiesis – is defined as the formation of blood cells. Haemopoiesis occurs in the bone marrow, liver, and spleen.
Option C- Bones help in the attachment of muscles to the bone by ligaments and bones to bones are attached by tendons.
Option D- is the incorrect answer because bones have no role in the formation of hormones and their secretion.
Hormones are directly secreted to the targeted organs, hence also known as ductless.
So, option D, Secretion of hormones, is the correct answer.

Note:Femur or thigh bone is the longest and stapes in the ear is the smallest bone in the human body while the spine is the weakest bone. Bones are generally made up of calcium, proteins, and estrogen hormones. Some bone disorders are- osteomalacia which is caused due to protein deficiency, osteoporosis caused due to decreased level of estrogen, tetany due to low calcium level in body fluid, gout due to the accumulation of uric acid crystals.