Jet lag occurs when a person moves rapidly from one time zone to another, causing conflict between the body's biological rhythm and the new cycle of light and dark. Some scientists suspect that jet lag may result from disruption of a daily hormone cycle known as .
a) epinephrine
b) insulin
c) melatonin
d) estrogen
e) prolactin

c) melatonin

Explanation:

Melatonin its a hormone formed by the pineal gland, which regulates an individual wake cycles and sleep. Jetlag alters the hormone function leading to an alteration with the body clock of the persom.

Jetlag is a sleep disorder common to those who travel swiftly over several time zones. It is not a permanent sleep disorder. Its due to the body's internal clock lacking sync with cues generated in a different time zone, Cues may be due to light exposure and how often the person eats.

A basic factor on ones internal clock is sunlight. It controls the regulation of melatonin which aid in synchronizing cells in the body.

Specific cells of the tissue at retina moves the light signals the thypothalamus.

At night, the hypothalamus signal to the pineal gland to produce melatonin. At daylight hours, the reverse is the case.

igneous rocks are formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.  

the composition depends on the source magma. there are almost a thousand types of composition found till now.  

hope this

i am sorry but i need more information and a picture.