AHSME 1980 Problem 4

In the adjoining figure, CDE is an equilateral triangle and ABCD and DEFG are squares. The measure of $\angle GDA$ is $\text{(A)} \ 90^\circ \text{(B)} \ 105^\circ \text{(C)} \ 120^\circ \text{(D)} \ 135^\circ \text{(E)} \ 150^\circ$