Which of the following responsibilities does the USDA hold?

The USDA is responsible for enforcing and amending the Animal Welfare Act, which is a key legislation that aims to ensure the humane treatment of animals used in research, exhibition, transportation, and by dealers. By overseeing compliance with this act, the USDA plays a critical role in setting standards for animal care and use, which is essential in laboratory settings. This responsibility extends beyond merely regulating food production or agricultural research; it encompasses the welfare of animals in various settings, highlighting the agency’s commitment to ethical standards in all animal-related activities.

The other responsibilities mentioned in the options do not accurately reflect the USDA's broader mandate. For example, the USDA's role is not limited to food production, nor does it focus solely on drug safety in humans. Additionally, while the USDA may provide grants for research, its responsibilities extend well beyond that specific area to include animal welfare through the enforcement of laws like the Animal Welfare Act. Thus, option B correctly captures a significant aspect of the USDA's responsibilities related to animal welfare oversight.