I also struggled with Met exam and this question has just reminded me why.
Working it out on my CX2 computer gives an answer of 1841ft which makes A the closest answer. (Cheating I know)
Reading Thom again, it would seem that you need to work it out on the DALR of 3 degrees per 1000ft. This would agree with the computer +/- a few feet.
I'm probably wrong, but as I said I struggled with the Met exam.
