HEY CAN ANYONE PLS ANSWER THESE PLS

Which explanation describes the forces involved for a person to walk down the sidewalk? a. the person's feet push backward on the sidewalk; the sidewalk pushes backward on the person. b. the person's feet push forward on the sidewalk; the sidewalk does not push on the person. c. the person's feet push backward on the sidewalk; the sidewalk pushes forward on the person. d. the person's feet push forward on the sidewalk; the sidewalk pushes forward on the person.

Because light travels in a straight line and casts a shadow, isaac newton hypothesized that light is

Aspacecraft that renters the earth’s atmosphere drastically slows down. the amount of kinetic energy the spacecraft has as it reenters the earths atmosphere