至于楼上说的,句子的意思只能是choose (one kind of music) among hard rock, soft pop, and "beautiful music" slopes
注意,是“beautiful music” slopes而不是beautiful music slopes,是有个双引号的,表示“beautiful music” slops是个特定的种类,而不是简单的形容词+名词。"beautiful music"是和hard rock, soft pop并列的。要是理解为skiers can choose "beautiful music" slopes among hard rock, soft pop的话,已经完全改变原句意思了(另外,要是这样的话,也不是among了,而应该用between了)。
trying to answe it. 如果一定要说原因的话,我觉得这个因果太牵强,比如说gmat选择题解题规则 比较 becz you can choose among a,b and c, you don't have other options. vs you can choose among a,b and c, and/but you don't have other options.