The provided Java program lacks completion and will not compile. Assuming completion with a simple `start()` method, the output would be "12 : 12" due to the print statement within the method. Option C is correct.
The provided Java code is incomplete and won't compile successfully. It lacks the closing brace for the `start()` method and the class. Assuming the completion is as follows:
class simple {
 public static void main(String[] args) {
 simple obj = new simple();
 obj.start();
 }
 void start() {
 int a = 5;
 int b = 7;
 System.out.println(a + " : " + b);
 }
}
The correct output would be:
C. 12 : 12