B) honey
A shirt is a solid, and helium is a gas at room temperature. A nebula is... not an object.
The reason scientists believe this is that there was basically no oxygen in the atmosphere at this time, which meant that cells needed to be anaerobic to survive,<span> going around the problem of no oxygen in the atmosphere.
Hope this helps.</span>
Answer:
treatment, treatment, control
Indep. Var.
Dep. Var.
Dep. Var