What happened that allowed cells to be studied? A. Cells increased in size

B. Scientist began to work together.

C. Scientists became smarter.

D. The microscope was invented and improved.

D

Explanation:

regents of the university of california v. bakke, 438 u.s. 265 (1978), was a landmark decision by the supreme court of the united states. it upheld affirmative action, allowing race to be one of several factors in college admission policy.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.