What are the three types of economy and what are their main characteristics?

What are the answers for the following questions?

If a volcano’s magma is high in silica, the volcano will probably a. erupt quietly. b. remain dormant. c. erupt explosively. d. produce dark-colored lava.

Which statement best explains the relationship between an area's geography and the temperature of its surface water? areas at low altitudes have the warmest water because they receive the most direct sunlight. areas at low altitudes have the warmest water because they have the least change in temperature throughout the year. areas at high latitudes have the warmest water because their days are the longest. areas at high latitudes have the warmest water because they have the longest seasons.