Why Can Type I Error and Type II Error Not

Why can Type I error and Type II error not be both present for one given hypothesis?

A) Power analysis makes one type of error less likely.
B) One refers to rejecting the null hypothesis when it is true and the other to accepting it when it is false.
C) As beta rises, alpha falls.
D) The researcher sets both the alpha level and the beta level.
E) Qualitative research does not use power analysis.