The correct answer is D. setprecision(2).

The setprecision() function is used to set the precision of a floating-point number. The precision is the number of digits that are displayed after the decimal point. For example, if you use setprecision(2), the number 123.456 will be displayed as 123.46.

The other options are incorrect. The setdecimal() function does not exist in C++. The setiosflags() function is used to set the format flags for an output stream. The 2.00 in option C is not a valid format specifier.

Here is an example of how to use the setprecision() function:

“`c++

include

int main() {
double x = 123.456;
std::cout << std::setprecision(2) << x << std::endl;
return 0;
}
“`

This code will print the following output:

123.46