Puzzle of the week #240

Chess Diagram: 

[Event "Puzzle #240"][Date "2013.12.08"][Result "1-0"][SetUp "1"][FEN "r7/8/8/8/5R2/4k3/8/4K2R w K - 0 1"]

This interesting position from a manuscript dated on the year 1500 shows that you do not need many pieces to create a beautiful puzzle. Your tasks:
a) What is Black using now to attack Rf4 and mate on the a1-square in the same time?
b) What should White do now? (plan - explanation)
c) White to move. Play the best line you can think of

Total available points for this puzzle is 25. The answers will be published next week together with puzzle #241.

Puzzle #239 solution:
Liwen Gu - Valer Eugen Demian, Langley chess club corr. tmt 2013. There were all sort of answers on this one and nobody managed to get them all right. The hardest was (b) because all of you do not have a lot of experience with it; however the first one proved to be difficult as well which is surprising when we remember we did talk about this opening. Here are the answers:
a) The opening name is 4 Knights
b) Black stays better because:
- it has more pieces in the center
- White has double pawns on the c-file
- White has all pieces badly placed (including the Bishops pair)
c) Solution:

[Event "Puzzle #239"][Date "2013.12.01"][Result "0-1"]1.e4 e5 2.Nf3 Nf6 3.Nc3 Nc6 4.d4 Bb4 5.Bg5 h6 6.Bh4 g5 7.Bg3 Nxe4 8.Qd3 Bxc3+ 9.bxc3 d5 10.Bxe5 f6 11.Bg3 Bf5 12.Be2 {Solution} Nxg3 13.Qb5 {In the game} ({Better is}13.Qe3+ Ne4 {Black is up a piece}) 13...Nxh1 14.Qxb7 Bd7 15.O-O-O Nxf2 {Black is winning}

Correct solutions:
Toro, Brian - 20 points
Bradley - 17 points
Brandon, Dheera, Oliver, Anya - 15 points
Benjamin - 12 points
Coco, Eric, Jalen, Jeffrey - 10 points
Illya, Aaron, Ken - 5 points
Cody - 1 point

Toro - 129 points
Brandon, Bradley - 107 points
Oliver - 105 points
Jalen - 98 points
Eric - 92 points
Coco - 91 points
Anya - 90 points
Brian - 85 points
Illya - 74 points
Benjamin - 65 points
Cody - 61 points
Jeffrey, Mrinal, Aaron - 40 points
Dheera - 15 points
Ken - 5 points


Double attack (1)