Which of the following statements is true?
a) when you drive a car, pressing its gas pedal sends a message to the car to perform a task—that is, to go faster.
b) you send messages to an object; each message is implemented as a method call that tells a method of the object to perform its task.
c) a program might call a bank-account object's deposit method to increase the account's balance.
d) all of these statements are true.