I just realized that B and C are ambiguous. Do you mean kingdoms in which the "sea of X" will win/lose or kingdoms in which the normal player will win/lose?
Isn't that synonymous, since when one wins the other loses? Let me try to explain in a bit more detail, in case it is ambiguous...
Set up one game in which:
- One player starts with exactly 7 coppers and 3 estates, and the other player starts with exactly 50 copies of any one card of your choice and no other cards.
- There are 10 kingdom cards available, of your choice.
- The player who started with exactly 7 coppers and 3 estates will win more than 50% of the time.
Then, set up one game in which:
- One player starts with exactly 7 coppers and 3 estates, and the other player starts with exactly 50 copies of the same card as the one chosen above.
- There are 10 (probably different) kingdom cards available, of your choice.
- The player who started with exactly 7 coppers and 3 estates will lose more than 50% of the time.