Registered Behavior Technician (RBT) Practice Quiz

A phase change line refers to the boundary between two phases of matter (such as solid, liquid, or gas) in a phase diagram. It marks a change in physical condition or state of matter, not just a simple adjustment or data shift. While the other options may have some relevance to scientific concepts, they do not accurately describe or define a phase change line. Therefore, the correct answer is B, as it specifically relates to the question and its scientific context.