Despite the seemingly ______ nature of the artist's early works, a closer examination reveals a profound intellectual rigor guiding each brushstroke.

✓ Correct Answer: Option A

The sentence implies a contrast: the works seem simple/childish, but are actually rigorous. 'Puerile' means childish or silly, fitting this contrast. 'Prosaic' means dull, 'profound' means deep, and 'pedantic' means overly academic.