Why does Shakespeare use the word choose so often in the second scene of act 1

Portia is lamenting how she must choose a husband while she is bound by her late father's wishes. In the end she cannot choose who she really likes but must choose the man that passes her father's test.

O me, the word “choose!” I may neither choose whom I would nor refuse whom I dislike—so is the will of a living daughter curbed by the will of a dead father. Is it not hard, Nerissa, that I cannot choose one nor refuse none?