Why did Nelson Mandela pick FW de klerk as his vice president?

Contrary to popular belief, Mandela did not pick De Klerk as his vice president. Rather, it was through agreements at negotiations which saw De Klerk made vice president after the 1994 elections as he was leader of the second largest party in South Africa, the NP. The NP also had 6 ministers in Mandela's cabinet.

And slos had a Nelson Mandela party on it.