An example of a grad-school level question?
Which is a physical property of an apple?

An example of a grad-school level question?
Heat from deep in Earth's interior is transferred to its crust by which of the following?

An example of a grad-school level question?
In which environment would a white rabbit be best protected from predators?

An example of a grad-school level question?
Which of the following can provide the human body with long-term immunity against some diseases?