The locus of all points having a distance of 1 unit from each of the two fixed points a and b is

A.
a line parallel to the line ab 
B.
a line perpendicular to the line ab through the midpoint of ab 
C.
a circle through a and b with centre at the midpoint of ab 
D.
a circle with centre at a and passes through b 
E.
a circle in a plane perpendicular to ab and centre at the midpoint of the line ab
Correct Answer: Option B
Explanation
The locus of all points having a distance of 1 unit from each of the two fixed points. a and b is: a perpendicular to the (ab) through the midpoints ab