Elena is used to kissing her friends on both cheeks as a form of greeting in her native country. she notices that her new friends in the united states get uncomfortable with this, thus showing her she is violating her friends'
a. values
b. protocol
c. norms
d. standards

c. Norms.

Explanation:

When Elena noticed her friend getting uncomfortable when she kisses him on the cheeks as a form of greeting she was violating his norms.

Norms are something that is standard or typical.

In USA there they not used to kiss on the cheeks to greet their friends there would be some other norm of greeting someone.

only #2 represents an object at rest on a table.

in #1, there is no normal force due to the table; the object is accelerating downward.

in #3, the vertical forces are not balanced; the object is accelerating downward.

in #4, neither the vertical nor the horizontal forces are balanced. the object is accelerating upwards and to the right.