Which disease reduces bone density and causes the bones to becime brittle

osteoporosis

explanation:

Osteoporosis, or porous bone, is a disease defined by low bone mass and skeletal degeneration of bone tissue, starting to bone brittleness and an enhanced chance of breakages of the hip, spine, and wrist. Men, as well as women, are influenced by osteoporosis, a disease that can be anticipated and handled. In the United States, more than 53 million people either previously have osteoporosis or are at great risk due to weak bone mass.

since you have not provided the options here i   am going to give you general overview about hormone.hormone are actually the part of endocrine system in our body and produced by the endocrine glands. the hormones act like a chemical messenger   within human body. once produce by the glands they   travel through the blood stream and reach at specific or target tissue and organs   which result in control of our body function. the hormones are specific in their work and work on only the targeted tissue or organ   . with the of hormone endocrine system regulate the heart rate , metabolism, our mood and   growth as well as the development and even the sleeping cycle etc. they actually are the messenger for body cell and organs .