Consider a $4$ bit ripple carry adder with inputs $A[3$:$0]=0110$ and $B[3$:$0]=1111.$ What are the

results of full adder for bit $3?$

Cout $=0,$ Sum $=0$

Cout $=1,$ Sum$=0$

Cout $=0,$ Sum $=1$

Cout $=1,$ Sum $=1$