請依下文回答第 21 題至第 25 題
The next time someone says, “I smell danger in the air,” that might literally be true.
At the tip of the noses of mammals is a ball of nerve cells known as the Grueneberg ganglion, named after Hans
Grueneberg, the scientist who described the structure in mice in 1973. Grueneberg thought it was just a nerve ending. Only in
the last few years did scientists realize that the Grueneberg ganglion is a component of the olfactory system. But they still did
not know what the ganglion smelled. Recently, researchers in Switzerland report that they have figured it out.
All sorts of organisms, including plants, insects, and mammals, release “alarm pheromones” when they sense danger;
the pheromones waft through the air to warn others. Very little is known about the alarm pheromones of mammals other than
that they exist. Nonetheless, the Swiss scientists could collect the pheromones by simply stressing mice and sucking up the
air around them.
When other normal mice were exposed to the danger-scented air, they froze in their tracks. But mice whose Grueneberg
ganglia had been removed did not notice anything wrong and continued to wander around their cages without a care in the
world. 【題組】25 The word “olfactory” in the second paragraph can be replaced by “_____ .”
(A)neural (B)smelling (C)immune (D)manufacturing