A, B, C & D were largely sequential. The point being all had both STOVL and CTOL options, whereas the description you posted suggested that A was CTOL only and then B was STOVL only. The purpose of the various options was to explore requirement and/or displacement limits (aka perceived cost). They were to a degree the product of the "Coles reviews" where assertions about gold-plating driving size and cost were tested.
Assertions that STOVL was the only option are easily discounted, simply by examining the RINA papers presented in 1997/98 where it was clear that not only STOVL and CTOL had been considered, but also the comedy STOBAR option, with the equally hilarious NEF2000. Even in the requirements generation phases in 1992-96, CTOL was always considered, albeit with some rather interesting assumptions about always requiring organic tanking, primarily based on the premise that taking was related solely to operating mode, rather than a mix of mode and number of cabs in the air..