What was the relationship between presidents william henry harrison and benjamin harrison?

The principle of checks and balances is based on the notion that

As you drive in to school, you hear a random radio-show caller arguing that sun exposure really has not been shown to cause skin cancer and that some research suggests that skin cancer is completely genetic and not related to sun exposure at all. at the time, you think that this is a silly argument and that the caller does not know what she is talking about. however, two months later, you are outside without wearing sunscreen, and you find yourself remembering that you had read something about how the sun actually does not cause skin cancer. this process is evidence that has influenced your attitude

Which factor contributed to the rise of african empires such as ghana and mali ? a. their creation and involvement in trade networks b. they focused only on agricultural production. c. they didn’t engage in warfare with other nations d. their geographic location protected them from attacks.