As an airplane sport pilot applicant, you must take a 40 question multiple-choice test and score 70% or better. There are separate sport pilot knowledge tests for each category of light-sport aircraft (LSA) with unique questions for trike weight-shift control aircraft LSA pilots and for airplane LSA pilots.
FAA knowledge exam sample test questions
The FAA has published a sample of the test questions you can expect to see on the 40-question test. Here is a link to view sample knowledge test questions.