Question

Native grasses in many of the world’s grasslands have been replaced with _____

Answer 1

Definitely cereal grains because think of it- Cereal in general is a very popular food among folks because it's easy to buy, prepare, and eat. So anything that is convenient for consumption that will bring in money, of course it will replace native grasses.

Answer 2

I had to look for the options and here is the answer:
It is the CEREAL GRAINS that replaced native grasses in most of the grasslands in the world. This may be due to the growing agricultural activities and that the demands for these are high for the consumption of everybody.