Question 4140 : APO Resource Master definition meaning

In SAP S/4 1909 APO Resource Master definition for eg: WT-A20_1010_001, what does the last 3 digit 001 represents ?
(only one answer)

A) Production Version
B) Active or Non-Active Version
C) Capacity Category
D) Capacity Version
D) Finite Scheduling Identifier
.

Answer: C

WT-A20_1010_001
W = Work Center
T-A20 = is the ERP Work Center code
1010 = Plant/Location
001 = Capacity Category