Which of the following code segments prints a single line containing hello there with the words separated by a single space?

a. std::cout << "hello ";
std::cout << " there";
b. std::cout << "hello" , " there";
c. std::cout << "hello";
std::cout << "there";
d. std::cout << "hello";
std::cout << " there";

d. std::cout << "hello";
std::cout << " there";