EXPLAIN when we would fill out 3b in the image? also what is schedule EO? why do entities that receive k1s need to fill EO AND this 3b?

3 At the end of the tax year, did the partnership: a Own directly 20% or more, or own, directly or indirectly, 50% or more of the total voting power of all classes of stock entitled to vote of any foreign or domestic corporation? For rules of constructive ownership, see instructions. b Own directly an interest of 20% or more, or own, directly or indirectly, an interest of 50% or more in the profit, loss, or capital in any foreign or domestic partnership (including an entity treated as a partnership) or in the beneficial interest of a trust? For nules of constructive ownership, see instructions. If "Yes," complete (i) through (v) below