(6 points for the correct answer; 2 bonus point if you have…

(6 points for the correct answer; 2 bonus point if you have correctly answered a total of 9 questions among questions 1 through 11.)  Consider the following proof of the fact that the product of any two odd integers is odd:  Suppose and . Then and are two odd integers. Since is an odd integer, it follows that the product of two odd integers and is odd.  Is the proof valid?