Final answer:
A kitten can move without being pushed or pulled because it is a living organism capable of autonomous movement. In contrast, the road sign, bubble gum, and shadow require external forces to move.
Step-by-step explanation:
Out of the options given (road sign, kitten, shadow, bubble gum), a kitten can move without being pushed or pulled because it is a living organism, capable of autonomous movement. This means it can initiate movement on its own based on its biological processes and does not require an external force like a push or pull to move. This differs from inanimate objects, such as a road sign, which would need a force such as the wind to cause movement. Similarly, bubble gum is a non-living object and cannot move unless acted upon by an outside force. A shadow, while it may appear to move, is actually a projection of light blocked by an object and does not move independently; it changes position only when the source of light or the object casting the shadow moves.
Not all forces are as noticeable as when you push or pull on an object. Some forces act without physical contact, such as the pull of a magnet (magnetic force) or the gravitational pull of Earth (gravitational force). However, in the case of living organisms like the kitten, movement is a result of muscular contractions and voluntary neural responses, not an external force.