Final answer:
The correct C++ includes for the statement utilizing 'cout' and 'fixed' are and , as they contain the definitions and manipulators needed for standard output and format control.
Step-by-step explanation:
The C++ statement mentioned includes the cout and fixed manipulators, which are part of the C++ Standard Library for performing I/O (input/output) operations.
The cout object is defined inside the iomanip and iosteam header files, and is used to print output to the standard output device, usually the screen.
The fixed manipulator, which is used to control the decimal point format of floating-point values, also comes from the iomanip header.
Therefore, the correct answer to which includes are necessary to use both cout and fixed is option d) #include <iostream> and #include <iomanip>.
The correct answer is (b) #include <iomanip>.
The given C++ statement cout << fixed << a is used to print a value with a fixed number of decimal places. The #include <iomanip> directive is used to include the necessary library to use the fixed manipulator.
By including <iomanip>, you can use the fixed manipulator and format the output accordingly. The other answer choices don't include the necessary library for the fixed manipulator, so they are incorrect.