The I0 state of the canonical LR(0) set of the SLR(1) parser of this CFG has how many productions?

Explanation

Augmenting the grammar with S' → S, the initial item set I0 is the closure of {S' → .S}. Since S follows the dot, add S → .AB; since A follows the dot there, add A → .CD; since C follows the dot there, add C → .[S] and C → .x. Closure stops here because each newly added item has the dot immediately before a terminal ('[' or 'x'), with no further nonterminal to expand. This gives 5 items: S' → .S, S → .AB, A → .CD, C → .[S], C → .x, so I0 has 5 productions.