which of the following is the biggest threat to the monarch butterflies annual migration?\na. illegal…

Brief Explanations:

Monarch butterflies migrate annually to specific oyamel fir forests in central Mexico to overwinter. Illegal logging in these protected areas destroys their critical habitat, removing the thermal cover provided by the tree canopy. This exposure makes the butterflies vulnerable to freezing temperatures and precipitation, leading to mass mortality. While climate change and pesticides are also significant factors, among the provided options, the destruction of their overwintering grounds via illegal logging is a primary and direct threat to the success of their migration cycle.

Answer:

a. illegal logging