The manipulated variable would be the moisture content.
Answer: Chlorophyll
Explanation:
Chlorophyll is the photosynthetic pigment found in the chloroplasts of green plants. It helps the plants to trap solar energy radiated from the sun during day light. This energy trapping by chlorophyll occurs during the Light-dependent stage (first stage) of photosynthesis, followed by Light-independent stage (second stage)
The concept would be crystallization. As magma cools inside or outside of the earth it crystallizes into an igneous rock. Intrusive (formed inside crust) igneous rocks are typically more course grained and contain many different noticeable minerals (for example, granite). Extrusive (formed outside) igneous rocks are typically more porous and are more fine grained then intrusive rocks (example, obsidian).
Answer:
it is c: Taking observations at precise intervals
Explanation: I just took the test.