yacc is which of the following parsers?

Answer: yacc is an LALR(1) parser.

Explanation: yacc is a parser generator that produces bottom-up parsers using the LALR(1) technique (Look-Ahead LR with one token of lookahead).

• Predictive (LL) parsers are top-down and work differently from yacc's bottom-up, shift/reduce approach.

• SLR is a simpler bottom-up method; LALR(1) is generally more powerful than SLR because it uses more lookahead information.

• CLR (canonical LR(1)) is the full LR(1) method with larger tables. LALR(1) merges compatible LR(1) states to produce more compact tables while keeping most of the LR(1) power.