Final answer:
The polynomial P(x) = 3 - 2x² + 5x⁵ - 7x⁷ has an order of 7.
Step-by-step explanation:
The polynomial P(x) = 3 - 2x² + 5x⁵ - 7x⁷ can be classified by its highest exponent. In this case, the highest exponent is 7, so the order of the polynomial is 7. Therefore, the correct answer is (a) 7.