Most alternative energy resources produce more energy at certain times. Which combination can produce a steady flow of energy from only alternative resources 24 hours a day year-round?
A Geothermal and natural gas
B Hydroelectric and geothermal
C Solar and petroleum
D Wind and coal

What are the two causes of density in deep current waters? a. salinity (how much salt) of the water and high temperaturesb. salinity (how much salt) of the water and low temperatures c. oxygen content of the water and high temperatures. d. oxygen content of the water and low temperatures