Which act made unfair and deceptive advertising practices illegal and granted oversight to the FTC?

The Wheeler-Lea Act is the correct answer because it specifically amended the Federal Trade Commission Act to address unfair or deceptive acts and practices in commerce, including advertising. Enacted in 1938, the Wheeler-Lea Act broadened the Federal Trade Commission's (FTC) authority to prevent deceptive advertising, ensuring that consumers are protected from misleading information about products and services. This legislation was significant in shaping the regulatory framework for advertising, allowing the FTC to enforce guidelines and punish violations related to misleading advertisements.

The other acts mentioned do not pertain to advertising practices. The Occupational Safety and Health Act focuses on workplace safety and health regulations, the Equal Employment Opportunity Act addresses discrimination in employment, and the Securities Exchange Act regulates securities markets and protects investors. These acts serve very different purposes and do not involve oversight of advertising practices.