Using one or more of your senses to gather information is called a. observing. b. inferring. c. predicting. d. classifying.

Using one or more of your sense to gather information is called "observing." Observation is when you gather evidence or information about someone or something. Observation is commonly used everyday, you use it as well. So the correct answer you are looking for is A. Observing 

1.989×10^30 kg is the weight of the sun.