Etiquette helps people to get along with each other.
Facts
causal: Etiquette helps people to get along, by preventing people from accidentally offending one another.
opinion: Many people think etiquette has no beneficial effects, while also thinking that kindness and social harmony are good.
Evaluate
Inference questions are all about synthesizing ideas. The first two ideas could be combined to yield, , since we know that "E helps to do X, by doing Y". That signifies that "Y and X have some causal connection".
The second sentence has some overlapping concepts with the first sentence, because they both bring up etiquette, and they both bring up people getting along / social harmony.
There seems to be an inherent contradiction in the opinions of these "many people": they think that etiquette does nothing beneficial, but they also think social harmony is beneficial.
Since etiquette helps bring about social harmony, it sounds like they're wrong in their thinking.
Goal
Look for an answer that suggests that the two beliefs these people have are in conflict, given the thing we were told about etiquette in the first sentence.