4. The fries had nearly 1,000 calories in them. Monica chose a salad instead.
The most effective way to combine these sentences would be:
a. The fries had nearly 1,000 calories in them, and Monica chose a salad instead.
b. The fries had nearly 1,000 calories in them, but Monica chose a salad instead.
c. The fries had nearly 1,000 calories in them, so Monica chose a salad instead.