Please Help with this multiple choice physics question!!

I think the answer is [ C.], am I correct?
If not, which is the correct answer? My book is useless! -_- I read the section over three times and it doesn't give a clear explanation!

THANK YOU!
http://d.yimg.com/hd/answers/i/75148088ea0d4da28c91b4996f1267d0_A.jpeg?a=answers&mr=0&x=1383157947&s=7bc1fd910cecd38d2e5c0b82a7e92d77

The correct answer is A. All spherical mirrors.

The same applies to concave mirrors. A good example is the curved pattern formed by light reflecting from the inside surface of a cup of tea etc. For this reason parabolic reflectors are used in such things as searchlights, film projectors and satellite dishes.

A the problem occurs where a mirror is spherical rather than parabolic.
If you draw a circle and do an accurate ray trace you find that the light which hits the edge of the mirror, at a distance 1r from the centre, continues in an almost straight line.
This ray, at least, does not pass through the focus.
At a point on the surface which represents 45 degrees from the centre the ray reflects out sideways ( 90 degree reflection) and this ray passes through a point which is r/(sqrt(2) from the centre.

And so on.
It only approximates having an accurate focus for very small angles.