John Deakin's articles are fantastic aren't they? I've learned quite a lot by reading his posts.
On another note:
One thing you may want to consider: on a C-172 and many other light singles, there is a little-known "feature" called (rather clumsily) full-throttle auto-rich. As the name implies, when the throttle is forward to the firewall, your mixture is automatically advanced to full-rich.
No, this is not true. You are thinking of the economiser function, which does enrich the fuel-air mixture at full throttle. It doesn't fully enrich the mixture, it simply adds a little more fuel in addition to the "normal" fuel jet in the carburettor or fuel distribution manifold. This is to provide extra fuel for cooling at sea-level full power.
When taxiing, it is possible to aggressively lean the mixture so the engine is just barely running at 1000rpm (or 1200 rpm, or whatever). If you advance to full throttle the engine stops. This would not happen if there was an auto-rich device.
The original question? I'd go for answer "c". Slightly enrich the mixture according to how much I'm increasing the throttle setting from cruise to full. Continue to lean during the climb i.a.w. that dodgy old collection of old wives' tales called the flight manual.
When arriving at TOC, re-lean the mixture according to how much I reduce throttle setting from climb to cruise.
Regards to all,
O8