Puzzle of the week #329

Level: 
2-Knight
Chess Diagram: 

[Event "Puzzle #329"][Date "2017.12.03"][Result "0-1"][SetUp "1"][FEN "4r3/pp3pkp/2p2np1/5b2/2P1r3/1P4PP/P2N1PB1/R3RK2 b - - 0 1"]

Material is equal. White has just moved Nf3-d2 forcing black to decide what to do about Re4. It is black to move and your tasks are:
a) Black to move and win
b) What option did white have to choose each time his King was attacked?

Total available points for this puzzle is 12. The answers will be published next time together with puzzle #330.

Puzzle #328 solution:
Puzzle by John A Bain, 2002. This week's best answers are by Glyn and Matthew:
a) The options are:
1. Capture the attacking piece = Qxh7
2. Moving away to cancel the attack = Nh4
3. Blocking the attack = cannot be done
4. Defend the attacked piece with another one = exf5
5. Counter attack a more important piece = Nge7+
6. Do none of the above and move another piece = Nxf6+

[Event "Puzzle #328"][Date "2017.11.26"][Result "1-0"][SetUp "1"][FEN "r1bq2k1/ppp2r1p/2np1pNQ/2bNpp2/2B1P3/3P4/PPP2PPP/R3K2R w KQ - 0 1"]1. Nxf6+ Qxf6 2. Qf8#

Correct solutions:
Joey, Lyvia, Darius, Glyn, Matthew, Itamar - 20 points
Ellie, Justin - 18 points
Eric - 15 points
Zheng Yu, Brian, Coby, Blake - 7 points
Lucas - 2 points
Glyn - 2 points for puzzle #327

Standings:
Matthew - 87 points
Lyvia - 80 points
Coby - 61 points
Eric - 59 points
Glyn - 55 points
Blake - 39 points
Justin, Ellie, Joey - 38 points
Darius - 30 points
Zheng Yu - 24 points
Brian - 22 points
Itamar - 20 points
Lucas - 11 points
Jacey - 3 points

Comment: 

Attacks and defences