Seller of the securitized assets

In the Fixed Income topic test, there is the following question:

In a securitization, the seller of the pool of securitized assets is the:

  1. Trustee

  2. SPE


According to the answer sheet, the correct answer is the depositor. But is this really correct? Doesn’t the depositor just sell the COLLATERAL to the SPE, and the SPE sells/issues the securitized assets to investors? Even in the book example, (Reading 54, Part 3.1 and 3.2) it says that the SPE issues the ABS and sells it to the investors.

The SPE sells bonds backed by the securitized assets, not the securitized assets themselves.