The correct answer is B. The ANC tried all other options before becoming violent.
Step-by-step explanation:
In a speech, the controlling idea is the main point in a speech, which includes the topic or issue the speaker will explain and the focus on it. Additionally, the controlling idea is explained using supporting ideas as well as evidence. This implies that in the speech of Mandela the focus is to explain how some of his actions were justified and why.
In this context, an appropriate supporting idea is "The ANC tried all other options before becoming violent" because the African National Congress led by Nelson Mandela first use non-violent strategies to fight against apartheid (system of racial segregation) in Africa; however, these strategies did not have a result and were responded by opposers with a massacre, which motivated the ANC to form a guerilla. Therefore, the actions of Mandela were justified or had a legitimate reason, and one statement that shows this is the fact the ANC and Mandela tried all other options before they considered violence, and violence occurred only because opposers responded with violence.