What is a disadvantage to hydropower dams? a. not every place is close to the ocean. b. people and animals can lose their homes to flooding. c. not every place receives many hours of direct sunlight. d. many pollutants are put into the air.

a graduated cylinder.

explanation:

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.