By picking his nose and belching several times at the lecture, Bob is violating informal norms.
What are informal norms?
These are expected standards of behavior that people are expected to abide by. They are not written down or enshrined in law but they are to be followed regardless.
Informal norms dictate that one shouldn't pick their noses or belch in public and Bob is violating that.
In conclusion, option C is correct.
Find out more on informal norms at https://brainly.com/question/8838403.
