Question

which influence is internal?
○ cultural background
○ health knowledge
○ likelihood of getting certain diseases
○ media messages

Explanation:

Internal influences are those that come from within an individual. Health knowledge is something that a person can acquire and internalize. Cultural background is a societal and external factor. The likelihood of getting certain diseases can be influenced by genetics (which could be seen as internal in a biological sense, but in the context of health - behavior influences, it's more of a biological predisposition rather than an active internal influence like knowledge). Media messages are clearly external.

Answer:

health knowledge