What did Raphael have to do before painting the fresco Assumed Portrait of Francesco Maria della Rovere, detail from the School of Athens?

a)  make a full-size cartoon for that part of the painting
b)  sketch the entire figure in charcoal on the wall
c)  grind pigments to mix with linseed oil
d)  mix melted beeswax into the colored pigment

a)  make a full-size cartoon for that part of the painting