Which of these postsecondary degrees comes after a master's degree (going from lowest to highest) ?

A. PhD

B. Bachelor's degree

C. High school diploma

D. Associate degree

From the given options, the degree that would come after the master's degree is (A) PhD. A PhD refers to Doctor of Philosophy, which is a doctoral degree that a person can pursue immediately after Bachelor's degree in some countries, or after a Master's degree. The other options are incorrect because a Bachelor's degree come before a Master's degree, while an Associate's degree comes before a Bachelor's degree, and a high school diploma comes before an Associate's degree.