单选题 Most analysts focus on the cost of tuition as the way to measure the cost of a college education. But incidentals,such as textbook costs,are rarely considered.A researcher at Drummand University wishes to estimate the textbook costs of first-year students at Drummand.To do so, she monitored the textbook cost of 250 first-year students and found that their average textbook cost was $600 per semester. Identify the sample in the study