Choice B is the best answer because it provides punctuation that creates two grammatically complete and standard sentences.
Choice A is not the best answer because it results in a comma splice as well as some confusion about what the prepositional phrase “from just a few primary colors” modifies.
Choice C is not the best answer because it results in a run-on sentence as well as some confusion about what the prepositional phrase “from just a few primary colors” modifies.
Choice D is not the best answer because it results in a comma splice.
