Horses, Cows, and Pigs.
Maize and Potatoes
Answer:
A. a replication of studies
Explanation:
A researcher performs a previous study following the same procedures to see if she will get the same results.This is an example of a replication of studies.
Carrying out a previous research under the same exact conditions to see if the results will be the same is simply a replication of study. Replication of studies is necessary for the validation of results gotten from the previous research.
The government controlled agriculture through collective farms.
Answer to 1st question: They dug irrigation systems and canals to get the water to their crops.
Answer to 2nd question: They knew how to boost the immune system and they knew how to get the body to produce more white-blood cells. They also had a 90% success rate on surgeries, including brain surgeries.
Answer to 3rd: He had a big army and long roads leading all over his empire so if there was an uprising his army could travel quickly.
Hope this helps, have a good day. c;