Which of the following describes the characteristics of a plasma? a. particles are packed closely together, have low compressibility, and usually maintain their organized, set shape. b. particles are positively and negatively charged, have high compressibility, and spread out to fill a container. c. particles move around in a semi-organized way, take the shape of a container, and fill a container from the bottom up. d. particles move freely, have high compressibility, and spread out evenly to fill a container.