How does cherokee's almost killing white fang become a good thing for white fang?

a.
losing the fight forces beauty smith to retire white fang.

b.
cherokee's almost deadly attack teaches white fang to look out for himself.

c.
almost having his dog killed shakes up beauty smith and makes him a kinder man.

d.
the cruelty of the fight attracts the attention of weedon scott.
"whitefang"

1. in which sentence is the underlined portion a predicate nominative? for astronauts, going into space to repair orbiting equipment becomes a challenge. for astronauts, going into space to repair orbiting equipment becomes tricky. for astronauts, going into space to repair orbiting equipment becomes challenging. for astronauts, going into space to repair orbiting equipment becomes frequent.