Which two CD markers are used to differentiate helper T cells and cytotoxic T cells?

What are cycloalkanes?

a. Compounds whose molecules are composed of only carbon and hydrogen atoms b. Compounds whose molecules are composed of carbon, hydrogen, and benzene rings c. Compounds that contain only carbon-to-carbon single bonds d. The first and last carbon atoms in a continuous chain are chemically linked to each other in a cyclic arrangement

Which of the following terms is not a "mechanism of injury"?

a. Blunt injury b. Rotational injury c. Stabbing injury d. Crushing injury