The heart is important for transporting oxygen to the muscles when we exercise. How does the heart rate change when we go from sitting on a chair to running up the stairs? A. The heart rate stops.
B. The heart rate gets slower.
C. The heart rate gets faster.
D. The heart rate stays the same.

Which statement correctly describes other ways in which nebulae and stars are different? a. a star always has a higher density than a nebula. b. stars can form inside a nebula but a nebula can never be produced by any star. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star. reset submit