为什么要选这个,而其他的不选,要在全班讲的It was not until the next morning__she found what she thought was the correct way to solve the prob

为什么要选这个,而其他的不选,要在全班讲的It was not until the next morning__she found what she thought was the correct way to solve the problem
A.what B,when C.that D.as选c为什么选C呢,先行词不是morning吗?