Which best illustrates the way in which radiation transfers thermal energy?

A red ball at left labeled warm does not touch a blue ball labeled cool at right. Curved arrows point from the blue ball to the red ball.
A red ball at left labeled warm does not touch a blue ball labeled cool at right. Curved arrows point from the red ball to the blue ball.
A red ball at left labeled warm touches a blue ball labeled cool at right. Straight arrows point from the blue ball to the red ball.
A red ball at left labeled warm touches a blue ball labeled cool at right. Straight arrows point from the red ball to the blue ball.