Scientists today learn about the world by . 1. using untested hypotheses to revise theories 2. observing, measuring, testing, and explaining their ideas 3. formulating conclusions without testing them 4. changing scientific laws

Option 2 (observing, measuring, testing, and explaining their ideas) is the correct choice.

Explanation:

A traditional perception of such a scientist is those of an individual who performs experiments in some kind of a white coat. The reality of the situation is, a researcher can indeed be described as an individual interested in the comprehensive as well as a recorded review of the occurrences occurring in nature but perhaps not severely constrained to physics, chemistry as well as biology alone.

The other three choices have no relation to a particular task. So the option given here is just the right one.

Iwannasay c is the most accurate

This is what a calorimeter is used for simpler ex, to measure calories in food.