Final answer:
The Ecology Center should recognize the present value of the pledge as contribution revenue using the present value technique.
Step-by-step explanation:
The Ecology Center should recognize the present value of the pledge as contribution revenue. Since the center uses the present value technique when measuring fair value, it is appropriate to record the present value of the pledge as revenue. The present value represents the current worth of future cash flow, taking into account the time value of money. Therefore, option c) is the correct way for the Ecology Center to record the pledge.