Marine Lieut. Col. Oliver North was a key figure in which 1980s controversy?

Oliver North was a central figure in the Iran-Contra Affair, a significant political scandal during the 1980s involving the clandestine sale of arms to Iran. The funds generated from these sales were then used to support the Contras, a rebel group in Nicaragua that was fighting against the Sandinista government, which was leftist and seen as a threat by the Reagan administration. This operation was controversial because it circumvented congressional prohibitions on aiding the Contras and raised serious ethical and legal questions regarding the actions of government officials. North's role in facilitating and managing this covert operation brought widespread attention to the scandal, making him a pivotal person in this controversy.

The other options involve significant historical events or controversies but are not directly linked to Oliver North's actions or the Iran-Contra Affair. For instance, the attempted assassination of President Reagan, CIA assistance to Afghani fighters, and the failed rescue attempt of American hostages do not encapsulate the illegal activities for which North was most famously known. Thus, option A accurately reflects both the actions and controversies associated with Oliver North during that era.