Refer to the input text as context and select the correct relationship between 'Freddie Mac' and 'mortgage loan' from the available options.
Options: platform, subsidiary, product/material produced, parent organization

Freddie Mac is guaranteeing four classes of senior securities issued by a third party trust, the FRESB 2015-SB2 Mortgage Trust, and is acting as mortgage loan seller and master servicer.
product/material produced