Which is true of an adjustable rate mortgage?

Assuming that this is referring to the same list of options that was posted before with this question, it is true that with an adjustable-rate mortgage the rate can be adjusted either up or down by the bank. 

The correct answer is a. when they started making tools that will them in cultivating lands, they could raise crops and that made them attached to one place for a longer period of time. after that, they started domesticating animals and building their own permanent settlements that resemble the ones we have today.