Final answer:
The correct definition of transmission is when light passes straight through an object, represented in the ray model of light as traveling in straight lines called rays.
Step-by-step explanation:
The correct definition of transmission in terms of light is: when light passes straight through an object. This can occur when light travels through empty space, such as from the Sun to Earth, or through various media like air or glass. The ray model of light represents this path of light as traveling in straight lines or rays. It is important to note that when light changes direction as it passes through an object, this is referred to as refraction, not transmission. Therefore, the correct answer to the definition of transmission is when light passes straight through an object.