What human activity uses the most water worldwide?
a. industry
b. wastewater
c. wells
d. agriculture

Agriculture is the human activity that uses the most water worldwide, with 70% from the whole water usage. Correct D Worldwide, agriculture accounts for 70% of all water consumption, compared to 20% for industry and 10% for domestic use. In some industrialized nations, industries consume more than half of the water available for human use.

the value of the 4 in the hundreds place is 400 while the value of th e 4 in the tens place is 40

400 is way bigger than 40.

the answer would be the third option, "no, ariel should have added 9^2 and 12^2 and compared that to 15^2."

this is found through the pythagorean theorem, which is a^2 + b^2 = c^2.

this is the correct way of solving the problem:

9^2 + 12^2 = 15^2

81 + 144 = 225

225 = 225