Among these two buffers, which does Basel 3 implement to reduce procyclicality and "promote the conservation of capital and the build-up of adequate buffers above the minimum that can be drawn down in periods of stress?"

I. Basel 3 will phase-in a capital conservation buffer of 2.5% (of RWA) comprised of common equity Tier 1

II. Basel 3 will phase-in a countercyclical buffer of between 0% and 2.5% (of RWA) to be determined by supervisors (national authorities)