Puzzle of the week #298

Level: 
4-Rook
Chess Diagram: 

[Event "Puzzle #298"][Date "2016.05.30"][Result "0-1"][SetUp "1"][FEN "6k1/5p2/3ppq1p/6p1/1P2P2P/3Q1P1K/2r3P1/6R1 b - - 0 1"]

In this heavy pieces endgame white has a passed b-pawn and intends to start pushing it forward as soon as Rc2 (under attack) moves away. Your tasks:
a) Why is it called a heavy pieces endgame?
b) Show black's best line to save the game
Total available points for this puzzle is 20. The answers will be published next time together with puzzle #299.

Puzzle #297 solution:
Game Geller – Novotelnov, Moscow 1951. The correct combination is:

[Event "Puzzle #297"][Date "2016.04.17"][Result "1-0"][SetUp "1"][FEN "5nk1/2b1q1p1/2p5/3pP1pQ/1r1P2P1/3B1R2/5PP1/6K1 w - - 0 1"]1. Rxf8+ Kxf8 (1...Qxf8 2. Bh7+ Kh8 3. Bg6+ Kg8 4. Qh7#) 2. Qh8+ Kf7 3. Bg6+ Ke6 (3...Kxg6 4. Qh5#) {Line "a" wins} 4. Qc8+ ({Line "b" also wins} 4.Qg8+ Kd7 5.Bf5+ Qe6 6.Qxe6+ Kd8 7.Qd7#) Qd7 5. Bf5+ Ke7 6. Qxd7+

Everyone showing either line (a) or (b) got points for their choice.

Correct solutions:
Benjamin, Bradley, Cody, Aaron Y - 22 points
Coco, Daniel - 18 points
Jalen, Ethan - 14 points
Yakov - 10 points
Aaron W - 8 points
Deryk - 1 point

Standings:
Jalen - 179 points
Bradley - 168 points
Coco - 125 points
Benjamin - 117 points
Daniel - 110 points
Deryk - 107 points
Cody - 105 points
Aaron W - 74 points
Ethan - 63 points
Yakov - 62 points
Aaron Y - 24 points
Shya - 10 points
Dheera - 5 points

Comment: 

7th rank domination