Question

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all the following are examples of observations, except:
a thermometer tells the scientist that the temperature is 30 °c (86 °f) outside.
the scientist sees that there are fewer birds in an area.
the scientist wonders what is causing changes to the ecosystem.
the ph meter the scientist uses in the river shows that the water is slightly acidic.

Explanation:

An observation in science is a factual, measurable, or directly perceivable statement. The first option uses a thermometer (a tool) to get a temperature value (measurable), the second is a direct visual observation (seeing fewer birds), the fourth uses a pH meter (tool) to measure water's acidity (measurable). The third option is a question or a thought about causes, not an observation.

Answer:

The scientist wonders what is causing changes to the ecosystem.