单项选择题

A.x =x0-(b)*k,y =y0+a*k
B.x =x0-(a/gcd(a,b))*k,y =y0+(b/gcd(a,b))*k
C.x =x0-a*k,y =y0+b*k
D.x =x0-(b/gcd(a,b))*k,y =y0+(a/gcd(a,b))*k