Final answer:
The time spent solving a math problem is a quantitative way to operationalize problem-solving ability, offering an objective measure that can be used in Jen's study on the effects of caffeine on problem-solving.
Step-by-step explanation:
Jen is studying the relationship between caffeine consumption and problem-solving ability. A quantitative way to operationalize problem-solving ability would be to measure the time spent solving a math problem. This approach provides a clear, numerical value that can be easily recorded and analyzed, allowing for objective comparison between participants. Unlike the other options, this method does not rely on subjective assessments or categorical variables and is directly related to the person's analytical skills and cognitive efficiency in tackling complex tasks.