Indigo Industries is considering two new machines. Machine A will generate revenues of $120,000, have variable costs of $40,000, and fixed costs of $8,000. Machine B will generate revenues of $140,000, have variable costs of $30,000, and fixed costs of $8,000. What is the incremental revenue? A : $10,000 B : $30,000 C : $0 D : $20,000