What is $$\angle A + \angle B + \angle C + \angle D$$ in the following figure?
I) $$x + y = 90^{\circ}$$
II) $$\angle A + \angle B = \angle C + \angle D$$

A

if the statement I alone is sufficient to answer the question.

B

if the statement II alone is sufficient to answer the question.

C

if the statements I and II together are sufficient to answer the question but neither statement alone is sufficient.

D

if both the statements I and II together are not sufficient to answer the question and additional data is required.