For the past 13 years, high school guidance counselors nationwide have implemented an aggressive program to convince high school students to select careers requiring college degrees. The government reported that the percentage of last year' s high school graduates who went on to college was 15 percent greater than the percentage of those who graduated 10 years ago and did so. The counselors concluded from this report that the program had been successful. The guidance counselors'reasoning depends on which one of the following assumptions about high school graduates? ['The number of graduates who went on to college remained constant each year during the 10-year period.', "Many of last year's graduates who went on to college did so in order to prepare for careers requiring college degrees.", 'Some of the graduates who went on to college never received guidance from a high school counselor.', 'Any college courses that the graduates take will improve their career prospects.']