The vast majority of first-year engineering students at Bighorn University are registered in Physics 121. Simone is registered in Physics 121; thus it seems likely that she is a first-year engineering student. Which one of the following statements, if assumed, enables the conclusion above to be properly drawn? ['The engineering program at Bighorn University is highly structured and leaves its students few opportunities to take nonscience elective courses.', 'Every engineering student at Bighorn University must pass Physics 121 or an equivalent in order to meet degree requirements.', 'The number of first-year engineering students at Bighorn University is slightly larger than the total number of students registered in Physics 121.', 'Some engineering students at Bighorn University take Physics 121 in their second year, but none take it in later years.']