instruction:
In this task you are given a sentence. You must judge whether subject of the main clause is singular or plural. Label the instances as "Singular" or "Plural" based on your judgment.
question:
A clump of cobwebs sprouted from the rotten scalp, drifting slowly in the frozen wind.
answer:
Singular

question:
If I worked fast enough, adrenaline put up a wall between me and my throbbing headache.
answer:
Singular

question:
His ears release pressure as they descend.
answer:
Singular