Carla drew a diagram to compare the roles of oxygen and hydrogen in photosynthesis. Which label belongs in the area marked Y?

Enters plant as a part of water
Combines with carbon dioxide
Is released into air through stomata
Is stored in leaves for later use

15. which of the following is not human-caused groundwater pollution? a. water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock. b. water in an aquifer is contaminated by leachate that seeps into the ground from a landfill. c. water in an aquifer becomes polluted with chemicals used in hydraulic fracturing, or fracking. d. water in an aquifer absorbs harmful bacteria from the drainage field of a septic tank.