Which of the following may happen to astronauts when they return to Earth from space? (1 point) a
They may feel dizzy because the flow of blood to and from the heart to the brain is affected in space.

b
They may feel dizzy because the heart pumps more blood per beat on Earth than in space.

c
Their heart rate may slow down because there is more blood to circulate around the body.

d
Their heart rate may slow down because there is less blood to circulate around the body.