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.

[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 .
[A]: serum


[Q]:  In newborn pigs , sympathetic nerves may attenuate hypertension - induced increases in blood flow to the cerebrum , but do not appear to affect flow to the rest of the brain .
[A]: blood


[Q]:  Relative phage haplotype frequencies in PAO1 samples , ( A ) planktonic , ( B ) biofilm 4 days , ( C ) biofilm 11 days .
[A]:
samples