Puzzle of the week #200

This is quite a messy position with both sides having some powerful batteries ready to destroy the opponent's last line of defence if given the opportunity. Black's last move was 17... d5 and White tries to figure out the best way forward. What should he do? Which piece to take? Can he afford not to take any? After a long analysis White decides to go with 18.cxd5 ... Your tasks:
a) Analyse the position and decide if White's choice is the right one
b) You must continue to execute Black's plan with the best moves you can think of
c) Could you guess what opening was played?
Total available points for this puzzle is 25. The answers will be published next week together with puzzle #201.

Puzzle #199 solution:
Warren - Selman, corr 1930 and Phipps - Davis, France juniors 1950 were identical games played 20 years apart. Surprisingly nobody has found the right answers for all questions and very few have identified the correct move order. Here are the answers:
a) See diagram
b) Budapest gambit
c2) See diagram
[Event "Puzzle #199"][Date "2012.05.28"][Result "0-1"]1.d4 Nf6 2.c4 e5 3.dxe5 Ne4 4.Nf3 d6 5.exd6 Bxd6 6.g3 Nxf2 7.Qd4 (7.Kxf2 Bxg3+ {Black wins}) 7...Nxh1 8.Qxg7 Rf8 {Black has the advantage}

Correct solutions:
James, Ziyao, Philip - 20 points (-1)
Jeffrey - 18 points
Daniel, Leo - 10 points
Derrick - 5 points
Alex, Justin, Kevin, Coco - 1 point

Standings:
Philip - 408 points
Ziyao - 350 points
Jeffrey - 311 points
James - 299 points
Daniel - 280 points
Leo - 275 points
Derrick - 251 points
Alex - 216 points
Leroy - 196 points
Coco - 190 points
Harmony - 187 points
Justin - 120 points
Kevin - 43 points