Final answer:
The National Institutes of Health (NIH) is considered the government's largest grant-making agency, greatly influencing medical research funding in the United States and contributing significantly to the GDP and job support.
Step-by-step explanation:
The government's largest grant-making agency is typically considered to be the National Institutes of Health (NIH), which is supported by federal grants and is a key entity in medical-related research funding. In 2011, NIH-supported research added an impressive $69 billion to the U.S. GDP and was responsible for supporting seven million jobs. The NIH, alongside other entities such as the National Science Foundation, the National Aeronautics and Space Administration (NASA), and the National Oceanic and Atmospheric Administration, play significant roles in the advancement of science and technology with the support of federal funding. In addition to medical research, federal grants also support a wide variety of other sectors, including agriculture through initiatives like the Agriculture and Food Research Initiative (AFRI), and education through land grants to universities.