Answer: A . to emphasize that there is still work to be done to repair the country
Step-by-step explanation:
Parallel structures are used when the speaker aims to convey the similar importance of different phrases or ideas enunciated.
Nelson Mandela spoke those words to remind the nation that work still needed to be done to repair the country. That they still needed to heal from their wounds and bridge the divisions they had amongst themselves. That it was time for them to build the nation.