Final answer:
a. High-intensity interval training (HIIT). The best option for Camilla's fitness goals is High-intensity interval training (HIIT).
Step-by-step explanation:
The best option for Camilla's fitness goals of increasing her level of cardiovascular fitness while decreasing her body fat would be High-intensity interval training (HIIT).
HIIT involves short bursts of intense exercise followed by short rest periods. This type of exercise has been shown to increase cardiovascular fitness, burn calories, and reduce body fat more effectively than continuous, low-intensity cardio workouts.
For example, Camilla could perform a HIIT workout by alternating between 30 seconds of all-out sprinting and 15 seconds of rest for a total of 20 minutes. This would challenge her cardiovascular system and help burn fat.