Final answer:
Mrs. Hale and Mrs. Peters deduce from the missing canary and its broken cage that Mr. Wright was angry about the canary singing.
Step-by-step explanation:
From the women's point of view in the play "Trifles," the clue that Mrs. Hale and Mrs. Peters uncover which shows that Mr. Wright was angry about the canary singing is (c) The missing canary from its cage. This conclusion is reached when they find the broken birdcage and eventually discover the dead canary wrapped in silk inside Mrs. Wright's sewing box, with its neck wrung. Given the context of the play, where Mr. Wright is described as a cold and hard man and Mrs. Wright had stopped singing, the dead canary symbolizes Mr. Wright's oppressive nature and the loss of Mrs. Wright's joy and music in her life.