Question

melanin is a substance produced by the epidermis, the outer layer of the skin. melanin absorbs harmful ultraviolet sunlight, thereby protecting the internal organs from these rays. although everyone has the same number of cells that produce melanin, not everyone makes the same amount of melanin. some people do not naturally produce much melanin; consequently, their skin appears lighter. for both lighter - and darker - skinned people, skin will start to produce more melanin as a result of being exposed to the sun for a long time. this is why a persons skin may appear tanner after vacationing in tropical climates.
match causes with their effects.
the epidermis is exposed to the sun for a long time.
internal organs are protected.
the epidermis appears lighter.
cause
some people do not naturally produce much melanin.
melanin absorbs the suns ultraviolet rays.
effect
the epidermis starts to produce more melanin.

Explanation:

• For the cause "Some people do not naturally produce much melanin", according to the text "Some people do not naturally produce much melanin; consequently, their skin appears lighter", so the effect is "The epidermis appears lighter".
• For the cause "Melanin absorbs the sun's ultraviolet rays", as the text says "Melanin absorbs harmful ultraviolet sunlight, thereby protecting the internal organs from these rays", so the effect is "Internal organs are protected".
• For the effect "The epidermis starts to produce more melanin", from the text "For both lighter - and darker - skinned people, skin will start to produce more melanin as a result of being exposed to the sun for a long time", so the cause is "The epidermis is exposed to the sun for a long time".

Answer:

• Cause: Some people do not naturally produce much melanin. → Effect: The epidermis appears lighter.
• Cause: Melanin absorbs the sun's ultraviolet rays. → Effect: Internal organs are protected.
• Cause: The epidermis is exposed to the sun for a long time. → Effect: The epidermis starts to produce more melanin.