Most of the modellers out there seem to think it is A, but that is all secondary sources.

You have almost certainly already seen all of this, but just in case….

A

http://www.scaleplasticandrail.com/kaboom/index.php/all-things-aviation/132-135-scale/132-aftermarket-items/771-spitfire-mk-viii-masks-and-brass-barrels-for-tamiya-kit-in-132

http://librarum.org/book/49815/96

http://www.modelarstwo.mdi.pl/sig/?spitfire-mk.viii-%28k48194%29,695

http://www.aviationbanter.com/attachment.php?attachmentid=63373&d=1367757018

T
http://www.aviationbanter.com/attachment.php?attachmentid=53727&d=1327584523

Interestingly the 2 pictures posted on aviationbanter came from the same source.