The molecule marked by blue question mark can be all of the following EXCEPT
The picture shown in the question can be of Cori cycle or glucose-alanine cycle which releases lactate and alanine respectively. Pyruvate is second intermediate in those cycles. (Look at treasure for Cori's pathway) But glycerol is released from adipocytes. So, it could not be the one marked by red question mark in the image shown in the question.
Pyruvate
Lactate
Alanine
Glycerol
Gluconeogenesis