Match the following:

Mining system	Face supports
a. Mechanized longwall in flat seam	1. Cable bolting
b. Blasting gallery method	2. Shield support
c. Mechanized longwall in steep seam	3. Alpine breaker line support
d. Wangawilli method for 3 m thick coalseam	4. Troika shield support

A. a-2, b-1, c-4, d-3

B. a-4, b-1, c-3, d-2

C. a-4, b-2, c-3, d-1

D. a-2, b-3, c-4, d-1

Answer: Option A