Final answer:
Brown v. Board of Education is the case that best fits the graphic organizer, as it directly challenged and overturned the 'separate but equal' doctrine established by Plessy v. Ferguson concerning public education.
Step-by-step explanation:
The best fits for the graphic organizer referencing a case that challenged "separate but equal" and was brought by students denied admittance to certain public schools based on race is B. Brown v. Board of Education. This landmark case in 1954 involved the Supreme Court unanimously overturning the Plessy v. Ferguson decision regarding public education. They ruled that separated schools were inherently unequal and violated the equal protection clause of the Fourteenth Amendment. The Brown case was a fundamental step toward desegregation and played an essential role in the civil rights movement, establishing that the mere act of segregating schools based on race induces a sense of inferiority among African American children that cannot be remedied by equality of tangible factors like funding and facilities.