D is the answer to your question
B) The fearsome unstoppable dog barked at us viciously needs a comma after fearsome and before unstoppable
(problem) I can't find my pen
(solution) ask someone to lend you one or retrace your day and look around for it.
I'm not sure if I answered this right but I tried
Answer:
Sentence two, "If my friend calls, tell them I'm at my violin lesson."
Explanation:
"Friend" is singular. "Them" is third-person plural.
