Ifeltsomewhatdisappointedandwasabouttoleave,somethingoccurredattractedmyattention.[A]unless[B]until[C]when[D]while为什么选C?请翻译句子

Question

I felt somewhat disappointed and was about to leave, ___ something occurred attracted my attention.
[A] unless [B] until [C] when [D] while
为什么选C?请翻译句子

Answer 1

when表同时.
译：当我觉得失望,正要离开的时候,有东西出现了,吸引了我的注意力.