Look at the questions below and decide which is declarative.
A. What happens when gasoline is mixed with water?
B. What is the difference in volume between hydrogen, oxygen, and nitrogen gasses at different
pressures?
C. What is the escape velocity of an object on Earth?

Im not sure but here is some information to help A declarative question is a yes-no question that has the form of a declarative sentence but is spoken with rising intonation at the end. Declarative sentences are commonly used in informal speech to express surprise or ask for verification.