When the hypothalamus receives signals of fear, the sympathetic nervous system activates which secretes the stress hormones epinephrine (adrenaline) and norepinephrine?

Read the following scenario to answer the following question. in some zoos, rare crosses between a male lion and a female tiger have produced hybrid offspring called "ligers." male ligers are sterile but some female ligers are fertile. in the wild, lion and tiger ranges do not naturally overlap, making such a cross unlikely. furthermore, the solitary behavior of tigers and the social organizations of lions create behavioral differences. applying the biological species concept, the sterility of ligers reveals that a. lions are probably a subspecies of tigers b. tigers and lions are the same species c. a new species called "ligers" is forming d. tigers and lions are separate species

Which description provides the best objective summary of the article in the passage?

Why do mountaineers become breathless as they reach high altitudes