Step 1: Understanding the passage.
In the passage, Mandela states: "not only was I not free, but my brothers and sisters were not free." This clearly means that his brothers and sisters also lacked freedom.
Step 2: Analyzing the options.
(A) free: Incorrect, because Mandela explicitly says they were not free.
(B) praying: Incorrect, there is no reference to praying in the passage.
(C) apologising: Incorrect, the passage doesn’t mention apologising.
(D) also not free: Correct — Mandela directly mentions this fact in the text.
Step 3: Conclusion.
The correct answer is (D) also not free.