Melanin, a dark brown pigment produced by the melanocytes, is responsible for determining the skin color of a person. If a person has more of this pigment, the skin color is dark, whereas having less of this pigment will make the skin light.

B. amount of melanin produced by each melanocyte

Smooth muscles are usually found in the linings or walls of most organs, such as stomach, intestines and blood vessels.

A. walls of blood vessels

Choices A, B, C, and D are all functions of the skeletal system. Choice E is the role of an integumentary system.

E. regulation of body temperature

ATP is the energy needed during cellular processes. This supplies the energy required for contracting muscles.

B. ATP

The neuromuscular junction serves as the area of communication or contact between a motor neuron and a skeletal muscle fiber. The production of a neurotransmitter called acetylcholine happens in this junction.

D. Acetylcholine

During muscle contraction, a cross-bridge is created between two proteins, which are the myosin (thick) filaments and the actin (thin) filaments.

A. Myosin

Ligaments are strips of tough yet flexible connective tissues that connect two bones together.

E. ligament

According to the graph, the lowest bone mineral content that is present in women, which is represented by the orange line, occurred at age 90 to 95 years.

E. 90-95 years

According to the graph, women have a lesser bone mineral content than men. When compared to men, women tend to lose more bone mineral content when they reach the age of 90 to 95 years.

A. women lose more bone mineral content as they age than men do