Which of the Following Techniques Is Correct for Palpation of the Rectum

Which of the following techniques is correct for palpation of the rectum?

A) Flex the finger,and insert it slowly toward the umbilicus.
B) First instruct the patient that this will be a painful procedure.
C) Insert an extended index finger at a right angle to the anus.
D) Place the finger directly into the anus to overcome the tight sphincter.