To answer this question, let's analyze the given code snippet:
System.out.format("Pi is approximately %d.", Math.PI);
The code uses the System.out.format method to print the value of Pi.
The format specifier %d is used to format an integer value. However, Math.PI is a constant with a double data type, which means it is a floating-point number.
Therefore, the code will throw an exception at runtime because the format specifier %d is not compatible with the double data type.
So, the correct answer is D) An exception is thrown at runtime.