Final answer:
A line graph is the most popular technique chart used by veterinarians to track and analyze changing variables related to animal health.
Step-by-step explanation:
Line graph: the most popular technique chart used by veterinarians
A line graph is often the most effective format for illustrating a relationship between two variables that are both changing. Veterinarians commonly use line graphs to track and analyze data related to animal health. For example, they may use a line graph to show the increase in body temperature over time when monitoring an animal's fever.
Keywords: line graph, veterinarians, variables, changing, data, animal health