In this task, you are given a sentence. You are expected to recognize the name of any form of chemical substances. Although there might be several correct answers, you need to write one of them.

Q: Study of the nematode putative GABA type-A receptor subunits: evidence for modulation by ivermectin.

A: GABA
****
Q: Hybrid carbon nanotube networks as efficient hole extraction layers for organic photovoltaics.

A: carbon
****
Q: Stimulation of N-methyl-D-aspartate receptors modulates Jurkat T cell growth and adhesion to fibronectin.

A:
N-methyl-D-aspartate
****