The elderly woman was (i) _________ to have returned to her the ring that she had lost fifty years before in the (ii) _________ waters of the Mississippi River.
In the first blank, you need a word like amazed. Dumbfounded is the only match. Turbid which is related to turbulent, is the right word to describe choppy waters in which something could easily be lost. (Turgid means “stiff” and tepid means “lukewarm.”)
