Purchase vs Pooling Method

On page 163 of the 2013 CFA book on Financial Reporting and Analysis, Question 19.

How is it that revenue is the same under the purchase and the pooling method? I though the pooling method consolidated the FSs retroactively, so before the acquiistion date. On the other hand, the purchase method will pro rate revenue and include it only from the date of acquistion onwards. Therefore revenue will be higher under the pooling of interests method for the current financial year assuming it wasn’t acquired the very first day of the year, right? Or am I wrong?

Can anyone please explain the difference between the pooling and the purchase method. Thank you so much

Basically pooling is done at hostrical values and purchase is done at fair value