Which set of words are only nouns?
Pompous, ridiculous, photographic
Penance, science, porous
Analysis, praxis, thesis
Poisonous, vocalize, stupidity
Analysis[countable/uncountable noun], praxis [formal noun], thesis [singular noun]are all nouns.
Pompous [adjective], ridiculous [adjective], photographic [adjective];
Penance[noun], science[noun], porous [adjective];
Poisonous[adjective], vocalize [verb], stupidity[noun].
Therefore, Analysis, praxis, thesis is the correct option.