Question

Why do you think scientists use multiple markers to identify individual elephants?

Answer 1

When a scientist is performing genetic tests in order to identify a specific individual they use specific markers that are found in the short-tandem repeat section of the DNA sequence. These regions are the most variable among the individuals that belong to the same species, therefore they are the best choice for trying to identify a specific individual.
The more markers they use, they can be more certain that this is a specific individual, in our case an elephant.