Casebook question

[Mike51]

NF 10.2.2 This is about double fouls and how the team last in possession can retain the ball after declining the opponents foul.

In situation A it states .....when B the "clean hands" team, retains possession by declining B's foul, the penalty for B's foul must be enforced.

In situation C, the play described states just the opposite. B get possession on the last timed down of the 4th quarter and clips on the advancement. Team A held prior while the ball was loose (fumble).
B declines A's holding foul and then A declines B's clip and the game is over because there was no accepted foul on the play.

I am confused. Which is it and what is the difference?

The plays are on page 84 in the 2008 NFHS Casebook