This one should be easy, as easy as A,B,C
A bit of learning early on, the Welsh Alphabet consists of 29 letter - A, b, c, ch, d, dd, e, f, ff, g, ng, h, i, j, l, ll, m, n, o, p, ph, r, rh, s, t, th, u, w, and y.
This might help you with the puzzle this week.
What you need to do is to take the first letter from the name of the feature - so a mountain such as Rhinog Fawr, the first letter would be 'Rh'. For a lake that is Llyn Gafr, the letter would be the 'G' rather than the 'Ll' that starts Llyn.
All you need to do is decide the multiple choice option for the 10th letter. The word is spelt out sequentially by these nine grid references:
SH 6260 2454
SH 6122 6130
SH 6454 5964
ST 1854 7970
SH 6298 2217
SH 6593 6044
SH 7226 4714
SH 5141 5307
SH 7026 2305
The tenth letter is either:
SH 6611 2339 or SH 8101 2736 or SH 6172 4955
What is the name of correct feature for the final letter?