Question

1. what significant technical innovation did donatello develop in relief sculpture during the early 1420s?

a. bronze casting techniques
b. rilievo schiacciato (shallow relief carving)
c. high relief stone carving
d. wood inlay methods

Explanation:

Donatello is known for developing the "rilievo schiacciato" (shallow relief carving) technique in relief sculpture during the early 1420s. This technique creates a very shallow relief, giving the illusion of greater depth through subtle modeling. Bronze casting (option a) is a casting technique, not specific to relief sculpture innovation here. High relief (option c) is a traditional relief type, not his innovation. Wood inlay methods (option d) are unrelated to his relief sculpture innovations.

Answer:

b. Rilievo schiacciato (shallow relief carving)