What happened to the 'g' in 'gwen'?
Adjectives mutate following feminine nouns. sgert is a feminine noun, so... gwen -> wen.
(As gwen is the feminine form of gwyn, is is most often seen as wen, since it usually only occurs when it is immediately following a feminine noun.)
I did not capitalize the 'a' and it was an error. It is a phrase not a sentence and the capital is optional, no?
I did not capitalize the 'A' and got the answer correct. You should even be able to leave the 'a' out. Maybe it was something else... 'a skirt white' would have been marked wrong.