I think it’s D............
Answer:
Radioactive labeling is a procedure used to monitor the path followed by a chemical element within a biological system to demonstrate the source.
Hypothesis:
The free oxygen produced during photosynthesis comes from water.
Procedure.
Single-celled algae were placed in four petri dishes containing carbon dioxide, glucose dissolved in Water.
In each box the oxygen was radioactively marked.
1 petri dish with CO2 marked. Experimental groups
2 petri dish with H2O marked. Experimental groups
3 petri dish with Glucose marked. Experimental groups (control)
4 petri dish with CO2 + H2O + Glucose, all marked. (control).
Gravity , Explosion
<u>Explanation:</u>
Nebulae are made of dust and gases—mostly hydrogen and helium. The dust and gases in a nebula are very spread out, but gravity can slowly begin to pull together clumps of dust and gas. As these clumps get bigger and bigger, their gravity gets stronger and stronger.
Eventually, the clump of dust and gas gets so big that it collapses from its own gravity. The collapse causes the material at the center of the cloud to heat up-and this hot core is the beginning of a star.
Water erosion is usually what people think of, but ice, wind and gravity can also cause erosion.
Water erosion is usually along rivers. As the water moves quickly by it rubs on the rock and dirt, causing rivers to slowly get wider.
Ice erosion is caused by glaciers. Sometimes it's a glacier rubbing against land, and there's a lake that was made by a glacier making it's way onto land and then melting.
Wind erosion is a big problem in fields and large open plains with loose dirt. The wind just blows all the dirt away.
Gravity can cause erosion and cliffs. Sometimes along a mountain or cliff the rock won't be able to hold itself up anymore, and gravity will pull it down.
Your answer would be all of them. Wind, water, ice, and gravity.
