Final answer:
The non-intact windshield would most likely explain the man's major open facial injuries after a head-on collision with a tree.
Step-by-step explanation:
The major open facial injuries sustained by the 20-year-old man after his vehicle struck a tree head-on could be most likely explained by the non-intact windshield. When a car undergoes a head-on collision, the force of impact can cause the windshield to shatter, resulting in significant injuries to the face and head.
The deployed airbag is designed to minimize serious injuries to passengers by reducing the force of impact and providing a cushioning effect. The bent steering wheel and crushed instrument panel may indicate the severity of the collision, but they are less likely to explain the specific injury pattern on the man's face.