Match the following, for standard diamond rods

Specification	Outer diameter in mm
P. AW	p. 34.9
Q. BW	q. 44.4
R. EW	r. 54.0
S. NW	s. 66.7

In standard diamond rod specifications:
AW corresponds to an outer diameter of 34.9 mm (P)
BW corresponds to an outer diameter of 44.4 mm (Q)
EW corresponds to an outer diameter of 54.0 mm (R)
NW corresponds to an outer diameter of 66.7 mm (S)

Matching these with the given options:
Option C correctly matches:
P (AW) with q (34.9 mm)
Q (BW) with r (44.4 mm)
R (EW) with p (54.0 mm)
S (NW) with s (66.7 mm)

Therefore, Option C is the correct match for the standard diamond rod specifications.