What is the definition of a proviso?

Match the author with the description a. ernest hemingway b. john steinbeck c. robert frost d. langston hughes (1) summers spent in pacific grove, california influenced the symbolism in his literature (2) his poetry includes simple, direct language. many are dramatic monologues written in free verse are about life on new england farms (3) the mood and tone of his literature is largely shaped by his experience as a soldier in world war 1 (4) his poetry and short stories include dialect and colloquialisms which gives his primarily african american characters distinctive voices