Which of the following relation is true for two digital signals A and B?

A

$$\overline{A + B} = \overline{A} . \overline{B}$$

B

$$\overline{A + B} = A.B$$

C

$$\overline{A + B} = \overline{A} . \overline{B} + A.B$$

D

$$\overline{A + B} = \overline{A} . B$$