What is a top-down parser?

A. Begins by hypothesizing a sentence (the symbol S) and successively predicting lower level constituents until individual pre-terminal symbols are written

B. Begins by hypothesizing a sentence (the symbol S) and successively predicting upper level constituents until individual pre-terminal symbols are written

C. Begins by hypothesizing lower level constituents and successively predicting a sentence (the symbol S)

D. Begins by hypothesizing upper level constituents and successively predicting a sentence (the symbol S)

Answer: Option A