Step 1: Understanding historical context.
South Africa held its first democratic elections open to all citizens regardless of race in 1994. This was a landmark moment in the history of the country and marked the end of apartheid.
Step 2: Role of Nelson Mandela.
In these elections, Nelson Mandela, leader of the African National Congress (ANC), was elected as the first black President of South Africa.
Step 3: Elimination of incorrect options.
- (A) 1990: Important year for the release of Mandela from prison, not the election year.
- (B) 1950 and (D) 1984: Both incorrect; apartheid policies were still in place.
- (C) 1994: Correct answer.
Final Answer:
\[
\boxed{1994}
\]