Why A
Two cards of equal weight say the true thing: the free plan is the primary route and the upgrade is optional. Each card names what it includes, with a navy tick, and never a cross or a dash, so the free card does not read as a lesser product. The routes line up at the foot. B joins the two into one panel, which reads well on desktop but turns into one tall panel on a phone. C belongs to the tier comparison pages. Built in components/plan-compare.css.
Copy rule: a visitor sees “Membership” and “Professional Track™”, and the join route is “Start Free Membership”. A signed-in member sees “Active membership” and “Activate your membership”, never “free” or “paid membership” (see the gallery). Drop the price line on acquisition pages.