Dr. james has decided that his 50th birthday would be the perfect time to begin writing an introductory psychology textbook. this would be a good time for dr. james to do this, as he has accumulated years of knowledge about psychology. it would be a demonstration of his:

A demonstration of his crystallized intelligence

The changes to agriculture in the united states since 1900 is that increased mechanization has increased food production, thereby increasing the need for labor. there has been an increased need for higher speeds of food production due the fact that the population in the united states continues to rise.