difference between normal and diameter in circle. A line through the centre of the circle meet the circle at two points is called
a)normal
b)tangent
c)secant
d)diameter
I am pretty sure that the answer is diameter but my notes say the answer is Normal.
Please explain.

A diameter is usually thought of as a line segment.  The lines described are indeed normal, and all normals to the circle are of this type.  But I am not comfortable with using "normal" as the name of such a line. 
Remark: It is odd that the sentence included "meets the circle at two points" since any line through the centre does meet the circle at two points. Perhaps the intention was to reinforce the "wrong" answer diameter. 
