When a person is frightened by a wild animal, what organ systems immediately become active?
A. endocrine and circulatory systems
B. Nervous and excretory systems
C. Digestive and circulatory systems
D. Respiratory and integumentary system‘s

In terms of alternation of generations, the internal parts of the pollen grains of seed-producing plants are most similar to a ) moss sporophyteb) moss gametophyte bearing both male and female gametangiac) fern sporophyted) fern gametophyte bearing only antheridia