Which of the following statements is true regarding hypertension in the United States? a. Only African Americans of a certain genetic variant are more likely than Caucasians to develop hypertension and have hypertensive vascular diseases than Caucasians. b. African Americans are just as likely to develop hypertension and have hypertensive vascular diseases than Caucasians. c. African Americans are more likely to develop hypertension and have hypertensive vascular diseases than Caucasians. d. African Americans are less likely to develop hypertension and have hypertensive vascular diseases than Caucasians.