While performing an experiment involving a reaction between two chemicals, the scientist observes that the reaction container has become warm. the observation is an example of: qualitative data quantitative data both qualitative and quantitative data the observation is not considered data

If he measures "How much warmer [which he should]," then he would be measuring quantity and B would be the answer.

Since he is only observing that the reaction container has become warmer, then qualitative data is all that he is measuring. The answer is A

C is not true "How much warmer" is not answered.

The observation is not a number but  it is a property. It is qualitative as color would be. (If a reaction changes color it would be qualitative).