(Question)
Q: Corals build hard exoskeletons that grow to become coral what? Choices: - beds - layers - crystals - reefs A:
(Answer)
reefs

(Question)
Q: What do light emitters do to what you see? Choices: - divide frequencies - subtract frequencies - block frequencies - add frequencies A:
(Answer)
add frequencies

(Question)
Q: Plants face two types of enemies: herbivores and what else? Choices: - erosion - water - carnivores - pathogens A:
(Answer)
pathogens