Final answer:
Option (c) Nelson Mandela was cautious and reserved during his period 'underground', reflecting his commitment to anti-apartheid efforts and the risks involved in his resistance activities.
Step-by-step explanation:
Nelson Mandela's attitude to life while he was 'underground' can be described as follows: c) Nelson Mandela adopted a cautious and reserved approach to life during his underground activities. This period of his life was marked by significant challenges as he led acts of sabotage against government properties in 1961.
Despite being a period of covert operations and living clandestinely, Mandela retained his commitment to the struggle against apartheid. The eventual arrest in 1962 and his subsequent 27 years in prison reflected the intensity and risks of his underground resistance.