Jeff is 13 years old and he has recently noticed some remarkable changes in himself. Over the past few months his voice has started to change, growing deeper. He has begun to grow pubic hair, as well as the beginnings of a facial beard. He is also filling out, with his muscles developing rapidly. These changes in Jeff are probably due to the action of .
a. gonads
b. thyroid gland
c. pineal gland
d. adrenal gland

In the mid 1800s western settlers and american indians differed in their views about

What impact did improvements in farming technology near the end of the nineteenth century have on the american economy? a. more energy was needed to power equipment, creating the renewable energy industry. b. less labor was necessary on farms, leading workers to pursue other jobs. c. less money was invested in farming as many locally owned farms went bankrupt. d. more demand for agricultural products reduced the price of food and animal products.

What is it called when countries build lots of weapons to store and them in case of a war?