Answer:
B.) Competition for mates
Step-by-step explanation:
Generally, species become endangered in the first place has to do with humans. If you analyze the other options, they each typically are caused by humans.
Poaching is illegal hunting or capturing of animals (endangered or not)
Clear-cutting is the same as deforestation, and causes habitat loss
Introduction of non-native species is typically caused by people who bring pets from other countries back to their native countries.
A competition for mates isn't normally something that causes a species to go endangered or extinct. The other options are much more threatening to this!