"Looks like we have some sick monkeys in here," he said. Some of the monkeys went berserk when they saw the space suits. They spun in circles in their cages or cowered in the corners. Others stared at the humans with fixed expressions on their faces.
"You see the clinical signs," Dalgard said, pointing to a monkey. "I feel pretty confident I can tell when a monkey is getting sick. They get a little bit depressed, they go off their feed, and in a day or two they are dead."
–The Hot Zone,
Richard Preston
Which statement is the best summary of the central idea of this passage?
Dalgard sees clinical signs of depression and illness in the monkeys.
The monkeys go berserk, stare with fixed expressions, and stop eating.
The monkeys are afraid of the men in space suits.
The monkeys do not show any signs of clinical depression or illness.