Passage Laparoscopy Is a Minimally Invasive Surgical Procedure Where Small Surgical

Passage
Laparoscopy is a minimally invasive surgical procedure where small surgical instruments are inserted into the body through cannulas (hollow tubes 0.5 to 1.0 cm in diameter) .  A cannula is inserted into the skin while sleeved around a trocar (Figure 1) .  The skin incision can be made directly with a sharp-tipped trocar as it is being inserted with the cannula.  If a blunt-tipped trocar is used, the incision is made beforehand with a surgical blade.  After insertion, the trocar is removed, leaving the cannula as an access point for laparoscopic procedures.
Figure 1  Cannula, trocar, and two types of tipsLow-friction trocars increase surgical precision and reduce postoperative scarring.  Friction between the skin and trocar tip is tested with synthetic skin and a stationary ramp whose surface is made of the same material as the trocar.  For testing, the synthetic skin is pressed against the ramp's surface by a load, weighted to allow the skin to slide down at a constant speed (Figure 2) .  In this setup, the weight of the synthetic skin layer is negligible.
Figure 2  Experimental setup to test the friction between trocar and skin
Adapted from W. Firme-Gustavo et al., (C) 2015 Society of Laparoendoscopic Surgeons.
-For equally sized trocar-cannula systems, incisions made for blunt-tipped trocars are smaller than those made by sharp-tipped trocars, forcing the skin to stretch more around the cannula.  This option better prevents slipping after the cannula is inserted because:

A) it decreases the contact surface area.
B) it decreases the static friction.
C) it increases the normal force.
D) it increases the coefficient of static friction.

Correct Answer:

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