Savannas differ from grasslands by having select one: . less annual precipitation. b. lower average annual temperature. c. no grazers. d. flat-topped trees scattered throughout.

D. flat-topped trees scattered throughout.

Explanation:

Grasslands are vast area of land covered in grass. In  such environment, grasses are favor to grow but trees shrubs and other tall plants are not favored to grow.

Savannas are also vast lands that supports the growth of grasses and trees scattered across the land.

So, in savanna there are trees scattered throughout the land and grasses, but grasslands only have grasses growing in the vast area.  

x would be the most and the least would be y because there are more fruit   and seeds than flock z has insects