Answer :
Final answer:
The variable x must be odd.
Explanation:
To determine which of the given options must be odd, we can rearrange the equation x = 50y + 69 to y = (x - 69)/50. If we let x = 69, then y = (69 - 69)/50 = 0. Since y is an integer, we can conclude that y can be even or odd depending on the value of x. However, since x = 69, we know that x is odd. Therefore, the correct answer is a. x.