Plane mirror always forms an image of same size as that of object
Concave mirror can form a virtual image that is greater than the size of object
convex mirror will always form a virtual image that is smaller in size
So overall for closer look during shaving in mirror we need a mirror that will form virtual image of greater size
So here correct answer would be
A concave mirror is used.
for this purpose the person should be closer to mirror as we know that image will be virtual and magnified only when the object is between focus and pole of the mirror