Final answer:
The correct answer is option 1. The Supreme Court ruling in Korematsu v. United States in 1944 referred to the security measure of internment of Japanese Americans during World War II.
Step-by-step explanation:
The security measures referred to in the Supreme Court ruling in Korematsu v. United States, handed down in 1944, is 1) internment of Japanese Americans.During World War II, the US government forcibly relocated over 120,000 Japanese Americans to internment camps based on the fear of espionage and acts of sabotage.
The Supreme Court, in a controversial decision, upheld the constitutionality of this internment under the Fourteenth Amendment.