D
Below the mountains ,the sunshine reflcts on the many lakes,making them shine like diamonds against the rich countryside.
山脚下,阳光照在星罗棋布的湖面上,使它们在富丽乡村景色的映衬下,如钻石般闪耀璀璨.
making动名词做主语,在这里构成非限定性从句.
against在这里是对照；对比：以…的布景或背景相对比的意思.against the rich countryside是在富丽乡村的背景/衬托/布景之下的意思.