C. Suffering. Siddhartha was a prince who spend all of his young years behind confined walls in a lavish estate. His father did this to prevent him from seeing the suffering that was common among the regular people. When Siddhartha climbed the wall in secret, he was astonished by the poverty, hunger, and disease among the commoners. This inspired him to seek inner understanding about ending suffering and started his path of becoming Buddha.
Short/simple answer: because it was forbidden to picture or sculpt anything figurative (i.e. representing a being or object). Figurative art could be wrongly interpreted as a depiction of Allah and worshipped instead of Him, and that would be considered idolatry.
