Jenny was very sad over the loss of the photos she had shot at Canada, ________ this was a memory she especially treasured.
A.asB.ifC.whenD.where在线课程A
解析：
句意：詹妮对她在加拿大照的相片的丢失很伤心，因为那段经历是她特别珍惜的。as表“原因”；
if表“条件”；
when表“时间”；
where表“地点”，根据sad over这个关键词可知as为最佳选项。