In prescriptive science investigations, scientists often make observations to understand the interacting parts of a complex A. Control B. Hypothesis C. procedure D. System

The correct answer is D.

Explanation:

Descriptive science investigation is a study model, according to which a phenomenon is approached and its elements are characterized and its conceptualized, according to a series of methods used for data collection and expression of the same, that is, through this type of research, which uses the method of analysis, it is possible to characterize an object of study or a specific complex system, point out its characteristics and properties. The main objective of this research is the relationship between the factors, the actors and the variables. Researchers not only collect data through  observation but are in charge of studying and analyzing to obtain meaningful results that can contribute to knowledge.

the supermassive black hole is in the middle of the galaxy.

i believe it would be c: tons.