9. Which of the following choices, if any, uses deductive reasoning to show that an odd number and an even number sum to an odd number?
a. \( ( 2 x + 1 ) + 2 y = 2 ( x + y ) + 1 \)
b. \( 2 x + 2 y + 1 = 2 ( x + y + 1 ) \)
c. \( 3 + 6 = 9 \) and \( 4 + 5 = 9 \)
d. None of the above choices