What are restriction enzymes? A. Carriers of foreign DNA into a cell that "restrict" the type of DNA introduced into the cell in the recombinant DNA technique. B. Protective enzymes found in some bacteria that "restrict" the type of DNA allowed in the bacterial cell by catalyzing the cleaving of other types of DNA. C. DNA of an organism that contains genetic material that comes from another organism and "restricts" the enzymatic activity of the host. D. Circular, double-stranded DNA found in the cytoplasm of bacterial cells that "restrict" the amount of DNA in the bacteria.