J.B.S. Haldane, an early 20th-century evolutionary biologist, was quoted saying "Would I lay down my life to save my brother? No, but I would to save two brothers or eight cousins." This statement makes sense according to Hamilton's rule (Br - C > 0). Why?
a) Because the benefit derived from each brother is 2.0, while from a cousin it is 1.0.
b) Because the cost of self-sacrifice is 1.0, while the gain of saving a cousin is only 0.125.
c) Because the genetic relatedness between a brother and a cousin is 0.5.
d) Because the cost of sacrificing for a brother is smaller than that for a cousin.
e) None of the above.