What are the two basic types of cells and how are they different (be specific). what are two things that all cells have in common?

What is the problem in this article? what solution does the article propose?

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -

3. draw a topographic map that displays the following features: (4 points each) a. the contour interval is 20 meters. b. the point of lowest elevation is 960 meters. c. the point of highest elevation is 990meters. d. there is at least one sinkhole or depression, at any elevation. e. there is at least one steep slope and one gentle slope.