Subunit vaccines are safer than traditional vaccines because they

A. Are acellular: Subunit vaccines contain only parts of the pathogen, not the whole cell or organism, which reduces the risk of adverse reactions.

B. Are administered in food: Vaccines are generally not delivered through food; this does not contribute to their safety.

C. Do not pose a risk for causing the disease: Because they contain only specific antigens and no live pathogen, subunit vaccines cannot revert to a virulent form or cause infection.

D. Are acellular and do not pose a risk for causing the disease: Subunit vaccines are acellular and composed of purified antigens, making them both safer and incapable of causing disease.

A. Transduction: Transduction is gene transfer mediated by bacteriophages (viruses that infect bacteria); Griffith’s experiment did not involve phage activity.

B. Conjugation: Conjugation requires direct cell-to-cell contact and transfer of DNA (often plasmids) via a pilus; Griffith’s work did not depend on cell contact.

C. Transformation: Transformation is the uptake and incorporation of free DNA from the environment by a bacterium; Griffith observed non-encapsulated cells acquiring traits from heat-killed encapsulated cells, which is transformation.

D. Cloning: Cloning refers to producing genetically identical copies or isolating a gene in laboratory techniques; this term does not describe Griffith’s natural gene uptake observation.