Question

which is the best hypothesis for the scientific question \how does light intensity affect the rate of photosynthesis?\
light intensity, co₂ concentration, and temperature are factors that determine the rate of photosynthesis.
light intensity has no effect on the rate of photosynthesis.
if the distance between the source of light and the plant is increased, the rate of photosynthesis will decrease.
light intensity has an impact on the rate of photosynthesis.

Explanation:

A hypothesis should be a testable statement. The first option lists multiple factors, not focusing on light intensity as the variable. The second option is too absolute. The fourth option is too vague. The third option, "If the distance between the source of light and the plant is increased, the rate of photosynthesis will decrease," is a testable statement that relates light intensity (distance from light source affects light intensity) to the rate of photosynthesis.

Answer:

If the distance between the source of light and the plant is increased, the rate of photosynthesis will decrease.