单选题：设有定义 `vector v(10); `

设有定义 `vector v(10); `
执行下列哪条语句时会调用构造函数? @[C](2)

A. `v[0] += "abc"; `
B. `v[0] = "2018";`
C. `v.push_back("ZUCC");`
D. `cout << (v[1] == "def"); `




A.`v[0] += "abc"; `
B.`v[0] = "2018";`
C.`v.push_back("ZUCC");`
D.`cout << (v[1] == "def"); `


答案：C