I've got a 90 degree dangle

What is the behavior of this code?

#include <string>
const std::string& get() {
    return std::string("hello");
}
int main() {
    const std::string& s = get();
    // use s
}
A

Well-defined only in C++17 and later

B

Well-defined: lifetime is extended by the const reference

C

Undefined behavior: dangling reference

D

Compile error