I believe the correct answer is: classical and religious
motives, principles of mathematics, perspective, and ideal proportions.
The main features of Albrecht Dürer's work are: classical
motives which he introduced into Northern art, through his knowledge of Italian
artists and German humanists; religious motives as he commemorated both
Lutheran and Episcopal Churches and the principles of mathematics, perspective,
and ideal proportions which he introduced in his theoretical works “Four Books
on Measurement” and “Four Books on Human Proportion”.