From the statements below, construct a direct proof to show that the product of two odd numbers is odd. Step 1 [ Choose] Suppose that a and b are two odd integers. There exist integers s and t such that a=2s+1 and b=2t+1. Their product is ab=(2a+1)(2b+1)=4ab+2a+2b+1=2(2ab+a+b)+1. Their product is (2a)(2b)=4ab. Step 3 Suppose that a and b are two even integers. There exist integers s and t such that a=2s and b=2t. Since ab can be written as 2(2ab), we know that ab will always be even. Since ab can be written as 2(2ab+a+b)+1, we know that ab will always be odd Step 4