Which answer choice does not contain any punctuation errors?
a. george said, "beavers fill the gaps of their dams with mud."
b. "bears, added charlotte, are also predators."
c. he noted "that wolves attack their prey in packs."
d. wolves, "todd noted," may be predators.

The only right answer is 'a' because we are reporting George's words in Direct Speech. In 'b' are also predators,should have been included in  the inverted commas. and in 'd' the word 'wolves' should also have been included,'c' is not a speech ,so there is no need for inverted commas.