In this task, you are given a sentence. You are expected to write the name of the organism substances in the body mentioned in the input. Although there might be several correct answers, you need to write one of them.

[EX Q]:  ( B ) Real - time PCR was performed on total RNA samples from the human brain regions known to express MOR1 .
[EX A]: samples

[EX Q]:  Residential proximity to the plant and younger age ( up to 13 years old ) were the strongest predictors of an individual ' s serum 2 , 3 , 7 , 8 - TCDD level .
[EX A]: serum

[EX Q]:  At the site of the atheroma rupture , platelet - released TxA2 leads to downstream micro - vessel contraction and thrombus propagation ( 7 ) .
[EX A]:
thrombus

