Which factor do venezuela’s varied climates depend upon the most?

The correct answer is - the relief.

Venezuela has multiple climate types, and the main reason for that is the relief of the country, namely the mountain ranges. The southern and southeastern part of the country is dominated by mountain ranges, the Guiana Highlands, Sierra Pacaraima, and Parima Mountains. The western and northwestern part of the country is dominated by the Andes, and there's also two smaller mountain ranges in the northern part of the country. Because of how the mountain ranges are positioned, Venezuela has wet tropical climate on the windward sides of the mountains on the south and southeast, as well as the ones on the north. The highest parts of the Andes have much cooler climate, while the leeward sides of the mountains and the interior of the country are much drier and warmer, being dominated by grasslands.