Question

aside from raising food yields from 50 to 67 percent, the movement from a two - field system to a three - field system resulted in:
a more people being needed on each manor to work the land.
b the introduction of irrigation systems.
c the use of fewer plough animals like oxen or horses.
d higher yields per acre and a more even distribution of labor throughout the year.
e lower yields per acre and increased labor output.

Explanation:

The three - field system allowed for more land to be cultivated each year compared to the two - field system. With the two - field system, half the land was fallow. In the three - field system, only a third was fallow. This led to higher yields per acre. Also, the planting and harvesting schedules in the three - field system (e.g., planting winter wheat, spring crops, and having fallow) distributed labor more evenly throughout the year. Option A is incorrect as the three - field system was more efficient and did not necessarily require more people. Option B is wrong because irrigation systems were not a direct result of the shift from two - to three - field. Option C is incorrect as more ploughing (due to more land under cultivation in a year) might have required more or at least not fewer plough animals. Option E is wrong as yields per acre were higher.

Answer:

D. higher yields per acre and a more even distribution of labor throughout the year.