Final answer:
Zach won the game as his score of -3.666... (repeating) is less than Vanessa's score of -3.625 when converted to decimal form.
Step-by-step explanation:
To determine the winner between Vanessa and Zach in their game, we need to compare their scores as decimals and decide which is less since the player with the lower score wins. Vanessa's score is negative 3 and 5/8, which can be converted to the decimal -3.625. Zach's score is negative 3 and 2/3; when converted to a decimal it becomes -3.666..., where the 6 repeats indefinitely. A negative number with a larger absolute value is considered lower in this context, meaning -3.666... is less than -3.625. Therefore, option C is correct, which states comparing the decimal equivalents of their scores shows that Zach won because -3.625 is greater than -3.666....