2 ptsBOfficial number: 7709
A properly adjusted external mirror on a passenger car shows:

Description
Regulation of the Minister of Transport, Construction and Maritime Economy of 13 July 2012 on the training of persons applying for driving licences, instructors and lecturers - Annex No. 1, pt. II.
Explanation
Correct answer: a part of the vehicle side and the space behind it corresponding to the vehicle side.
A correctly adjusted exterior mirror should show a small fragment of your own vehicle's side, as seen in the picture. This serves as a reference point for judging the distance and position of other road users. The main part of the mirror must cover the widest possible area of the road behind to minimise the so-called blind spot and ensure safety, for example, when changing lanes.