Which organization signed the Social Security Amendments of 1965 into law?

The Social Security Amendments of 1965, which established Medicare and Medicaid, were signed into law by President Lyndon B. Johnson. This legislation was a significant milestone in U.S. health policy, aimed at providing health coverage to elderly citizens and low-income individuals. President Johnson, recognizing the importance of these programs in addressing health care accessibility, pushed for their implementation as a vital part of his "Great Society" initiative.

The role of President Johnson in the enactment of these amendments was pivotal as he championed the expansion of social welfare programs and emphasized the necessity of providing health care for all citizens, particularly the most vulnerable populations. His administration worked to address inequalities in health care and ensure that older adults and those in financial need would have access to essential health services.

The other choices represent organizations or entities that do not play a direct role in signing legislation into law. While the National Health Service serves as a model for public health care in other countries, it is not related to U.S. legislation. The American Medical Association is a professional association that represents physicians but does not have legislative authority. The Centers for Medicare and Medicaid Services, established later, administers the programs created by the amendments but did not exist at the time of the signing.