A．They acquired this ability through recent evolutionary changes.
B．They are not necessarily more intelligent than other animals.
C．Their brains all have an identical structure that governs this ability.
D．They may be able to understand other animal's perspective.
A．Many of her books are bestsellers.
B．She is a shrewd bookstore owner.
C．She is promoting her book in person.
D．She is a salesperson at the bookstore.
A．It has been the bestseller for weeks.
B．It is being sold at a very low price.
C．It advises people to change themselves.
D．It distinguishes co-operators.