answers for article about smiling

a. The scientific explanation for smiling is that smile is not only the expression of an internal feeling but also only the most visible part of an intimate melding.

(I don't know exactly about this question. sorry)

b. They began to study the science of smiling by classifying smiles into a few categories

c. Smiles are not simply the expression of an internal feeling. Smiles in fact are only the most visible part of an intimate melding between two minds.

d. An embarrassed smile is often accompanied by a lowered chin, for example, while a smile of greeting often comes with raised eyebrows.

A dominant smile is accompanied by a flashed power grin as well — often raising their chin so as to look down at others.

A happy smile is accompanied by activity in the brain’s reward circuits, and looking at a happy smile can excite those circuits as well.

e. Yes. For example, salesclerks might be trying to woo the customer with a fake smile.