Unlike life at the top of a body of water, life at the bottom of the body of water a. must rely on other means than photosynthesis. b. receives much more exposure to light. c. is affected by temperature and nutrient availability. d. performs much more photosynthesis.

i have been stuck on this question for quite some time and cant seem to find the answer. : )

What do scientists need to look at before developing an argument

Turtle hatchling survivorship rate is low in many turtle species due to predation. amanda researched the predatory rate on a species of turtle eggs in the red river. the eggs were harvested from trapped turtles and the egg's cloaca film (reproductive discharge) was either washed off or left on once gathered. research suggests that predators use the female's cloaca scent to locate the eggs. the eggs were only handled when wearing gloves and then reburied along islands where the turtles were trapped. the nests were monitored by cameras and manually on foot and data on nest predation were recorded. a. based on the experimental design, what is the dependent variable? b. based on the experimental design, what is the independent variable? c. based on the experimental design, what is the control?

In which situations is the principle of cross-cutting relationship useful in determining relative age?