Which property is true for GCD(a,b)\text{GCD}(a, b)GCD(a,b)?
GCD(a,b)=GCD(b,a)\text{GCD}(a, b) = \text{GCD}(b, a)GCD(a,b)=GCD(b,a)
GCD(a,0)=a\text{GCD}(a, 0) = aGCD(a,0)=a
GCD(a,a)=a\text{GCD}(a, a) = aGCD(a,a)=a
GCD(a,b)=GCD(a,a+b)\text{GCD}(a, b) = \text{GCD}(a, a+b)GCD(a,b)=GCD(a,a+b)