Final answer:
Carbohydrate fermentation is positive if there is both a color change to yellow and gas production, hence option C) Positive for Both Color Change and Gas Production is correct.
Step-by-step explanation:
When recording the reaction of carbohydrate fermentation, it's important to observe the indicators of fermentation such as color change in the medium and the production of gas. A positive reaction for fermentation typically involves acid production, indicated by a color change to yellow due to a decrease in pH, and often gas production, which may be manifested as bubbles or a visible split in the solid growth medium. Therefore, a positive test for carbohydrate fermentation would be recorded as 'C) Positive for Both Color Change and Gas Production' if both a color change and gas production are observed.