单项选择题

Sydney promised her tht he wouldlwys donything he could for her to ________ of her hppines

s.[Sydney promised her tht he wouldlwys donything he could for her to ________ of her hppiness. [ ]mking sure B.be sure C.being sure D.mke sureA.making sureB.be sureC.being sureD.make sure