Final answer:
The correct answer to the question is option B) Moving. Kinetic molecular theory states that molecules in a gas are always in motion, with speeds that can vary widely.
Step-by-step explanation:
According to kinetic molecular theory, colliding molecules might be moving at high speed while others are nearly stopped. The correct answer to the question is option B) Moving. The kinetic molecular theory explains that molecules are in constant motion, and this motion increases with temperature. In a gas, many molecules move so fast that they collide billions of times every second. However, individual molecules cover only short distances between collisions, which means some are zipping about at high speeds while others may just be recovering from recent collisions and moving more slowly.