Which of the following are reasons the grain supply increased during the high middle ages? select all that apply.

a.
slash-and-burn agriculture

b.
the use of oxen to pull plows

c.
the use of wooden hand tools

d.
the use of the iron plow

e.
the use of the three-field system

The correct answer is D & E.

The availability of more modern and efficient factors of production during the High Middle Ages, such as the plow, multiplied the production possibilities frontiers in the societies. Moreover, three-field techniques allowed to enhance efficiency by rotating the cultives used on each allotment so that each period the maximum output is generated of different cultives, taking the largest possible profit from the soil nutrients.

Producers started to be able to harvest a largest grain output in the same exploitations. Therefore, the aggregate supply of grain grew.

b, the anti immigrant fervor