The correct answer is D. human.
Indeed, one of the main notions of the Renaissance was humanism. This philosophy posits that since we are all humans one fundamental principle of our culture is the value of human beings in all their facets, physical, spiritual, religious and social.
The Renaissance artists took very seriously the Bible, notably the Genesis passage about man being created in the image of God as the image below proves. You will notice that God is enclosed in a cloth that follows the same contours of a side view of the human brain.