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”.