Hello there, please help.

an increasing number of colleges and universities are offering research internships to high school to provide
them hands-on experience conducting research. In particular, biomedical research institutes
weeks and require students to assist scientists with a long-term research project. These institutes
that will prepare high school students for demanding scientific study in a postsecondary setting

In the underlined portion, the writer wants to show that such institutes are more challenging than high school summer programs. Which choice best accomplishes this goal?

a. scientific tasks
b. close supervision
c. NO CHANGE
d. informative lesson