Questions: Some people experience a mixing of the senses such that one sensation will trigger another sensation. This is called synesthesia.

The answer is the third one (or C): synesthesia.

Explanation for each option:

1. Selective anertion: This term does not exist in the context of sensory experiences or psychology. It appears to be a misspelling or a non-existent term.
2. Proprioception: This refers to the sense of the relative position of one's own body parts and strength of effort being employed in movement. It is not related to the mixing of senses.
3. Synesthesia: This is a condition in which one sense is simultaneously perceived as if by one or more additional senses. For example, a person might see colors when they hear music. This matches the description given in the question.
4. Sensory adaptation: This refers to the process by which our sensory receptors become less sensitive to constant stimuli over time. It does not involve the mixing of different senses.

Summary: The correct answer is synesthesia, which is the phenomenon where one sensation triggers another sensation, such as seeing colors when hearing music.