Final answer:
The volume of the vegetable oil could be 1 ounce, with the correct number of significant digits.
Step-by-step explanation:
When measuring vegetable oil using a measuring cup that has increments of 1 ounce, the volume of the vegetable oil can be expressed with one significant digit. Therefore, the measurement must be rounded to the nearest whole number. In this case, the volume of the vegetable oil could be 1 ounce (option A).