Question

which is considered a scientific observation?
akon explained that cells need energy which is why animals eat food.
jacinta correlated that high sweat levels were due to a high heart rate.
mahir noticed the plants he watered grew taller than those with less water.
kai decided plants are green because of the chlorophyll used to make food.

Explanation:

A scientific observation is a factual noting of something. Mahir simply noticed a difference in plant growth based on watering amounts, which is an observation. The others are explanations or correlations, not pure observations.

Answer:

Mahir noticed the plants he watered grew taller than those with less water.