All the questions are multiple choice. Most questions have 4 answers. At least 2 will be obviously wrong, so pick between the other 2 that seem more right. I dont remember any trick questions but NASM is heavy on particular vocabulary, so know and understand your vocabulary terms that are in bold on the text borders. You need to know postural deviations, exercise progressions and regressions, the OPT model (but not tempo, reps, and particulars). You will need to know how to describe the movements of an exercise using planar terms (extension, medial, etc.) You will need to know some basic assessment stuff (rules like you cant diagnose injuries). You also need to know special conditions for the elderly, obese, etc.
I just read the manual. The test was easier than I thought, which was a relief. I extended 2x because I didnt think I could retain all that info, but it wasnt bad. I recommend reading the book and then taking the test. If you fail, cover those chapters you felt weak in and retake the test immediatly.