Which of the following describes one of the drawbacks of fresco secco? a. Fresco secco didn't allow for the use of ultramarine blue paints. b. Gold leafing couldn't be applied to frescoes when using the fresco secco technique. c. Fresco artists could only work on one small section of a fresco at a time. d. Fresco secco was less durable than other techniques, and subject to peeling.