Final answer:
The Presidential Unit Citation is not established by an executive order, making option C correct. Executive Orders 9066 and 9981 dealt with Japanese American internment and military desegregation, respectively, not the Presidential Unit Citation.
Step-by-step explanation:
The Presidential Unit Citation is not established through an executive order. Thus, the correct answer to the original question is C) The Presidential Unit Citation is not established through an executive order.
To address the other options briefly: Executive Order 9066 was issued by President Roosevelt during World War II and authorized the military to remove Japanese Americans from the West Coast, which led to their internment. Executive Order 9981 was issued by President Truman in 1948 and called for an end to segregation in the military, promoting equality of treatment and opportunity for all members of the armed services without regard to race, color, religion, or national origin. Executive Order 13223 does not pertain to the Presidential Unit Citation.