Four. The human heart has four valves.
Because most STD (STI)s are bloodborne diseases, and the sexual contact is close enough to blood contact, or are on the genitals.
Answer:
mere exposure effect
Explanation:
The mere exposure effect is a phenomenon that causes a person to like something only because they are familiar with it.
Here, when Lem saw a certain trim detail at the beginning of the day. This caused him to become familiar with the design. At the end of the day he still likes the detail. This happened because he got familiarized with the design and he liked nothing else.
Hence, his behavior is influenced by the mere exposure effect