Question

what is a stimulus? *
the action of picking up an object
any aspect of or change in the environment to which an organism responds
the relationship between color and wavelength

what occurs when ones skin notes that the room just got colder? *
sensation
perception

Explanation:

• For the first question: A stimulus is defined as any aspect of or change in the environment to which an organism responds. Picking up an object is an action (not a stimulus), and the relationship between color and wavelength is a physical concept, not related to the biological/psychological definition of a stimulus.
• For the second question: Sensation is the process of detecting a physical stimulus (like a change in temperature). Perception is the interpretation of that sensation. When the skin notes the room got colder, it's the detection (sensation) of the temperature - change stimulus.

Answer:

• First question: any aspect of or change in the environment to which an organism responds
• Second question: sensation