28. On a hot summer day, Jack left the pool and began to climb a ladder to his tree house. He hurt his toe by bumping it on the ladder as he climbed into the tree house. How did Jack know that he had hurt his toe?
a. The nerves in his hurt toe sent a signal through his body to his brain.
b. The blood cells in his toe sent a signal through his body to his brain.
c. Jack's toes became very cold and numb.
d. Jack's toe became smaller than before he had bumped it on the ladder.