Which of the following is true if GCD(a,b)=d\text{GCD}(a, b) = dGCD(a,b)=d and kkk is a positive integer?
GCD(a+k,b+k)=d\text{GCD}(a+k, b+k) = dGCD(a+k,b+k)=d
GCD(a+d,b+d)=d\text{GCD}(a+d, b+d) = dGCD(a+d,b+d)=d
GCD(ak,bk)=dk\text{GCD}(a^k, b^k) = d^kGCD(ak,bk)=dk
GCD(a,b)=GCD(a,b+a)\text{GCD}(a, b) = \text{GCD}(a, b+a)GCD(a,b)=GCD(a,b+a)