Jenna is reviewing her friend Tammy's paper. She notices that Tammy’s grammar is incorrect in several places. What is a constructive way for Jenna to give feedback to Tammy?

A.She tells her other friends and the teacher that Tammy’s grammar is incorrect and then asks them to give Tammy advice.
B. She simply tells Tammy that her grammar needs work and leaves it at that.
C. She points out to Tammy where the grammar is incorrect and shows her how she can improve her grammar.
D.She uses Tammy’s paper to help improve her own paper.