See the discussion of this question here:
In this stimulus, completing two courses will be sufficient for Angela to get a degree in psychology, and taking the course in experimental design first is necessary for someone taking the course in developmental psych. This means that if she takes the developmental psych course, then she must have already taken the experimental design course, and once both are completed she will have earned her degree. So, we can conclude that completing the developmental psych course will guarantee that she has earned the degree.
Answer A is incorrect because we don't know how many terms one course takes. We only know that next term is the earliest that she can take the prerequisite course, and so the term after that is the earliest that she can take the final required course. That course could be completed in one term, but not the next term.
Answer B is incorrect because there is no evidence about the relative ease of the two courses, just that one must be completed before the other is taken.
Answer C is incorrect because no information is given about prerequisites for experimental design, only for developmental psych. Perhaps there are some, but perhaps not.
Answer D is incorrect because we don't know about anyone other than Angela, and even in her case we don't know that any particular course is necessary to earn the degree, but only that those two courses are sufficient for her to earn the degree.
Answer E is the correct answer and matches our prephrase. Once she has completed the developmental psych course, we will know that she also completed the experimental design course (because it had to be done first), and therefore she will have completed the two courses which are, taken together, sufficient for her to earn her degree.