Answer:
B. An angled and long femur indicates bipedalism because it allows for better balance when walking on two legs.
Step-by-step explanation:
When we look at the anatomy of bipedal animals, such as humans, we can observe that their femur, or thigh bone, is angled inward towards the knee joint. This inward angle, known as the "valgus angle," helps distribute the body's weight more efficiently, providing stability and balance while walking or running on two legs.
This valgus angle of the femur aligns the body's center of gravity over the hips and between the feet, which helps in maintaining an upright posture and prevents excessive swaying or wobbling during locomotion. Additionally, the length of the femur contributes to stride length and leg extension, enabling efficient movement and energy conservation while walking or running.
On the other hand, an angled and long femur would not necessarily support climbing in trees or indicate a preference for swimming. Climbing in trees typically requires flexible limbs and grasping appendages, while swimming is more related to adaptations in the limbs, body shape, and other features specific to aquatic locomotion.
In conclusion, the angled and long femur in bipedal animals is a crucial adaptation for walking on two legs as it promotes balance, stability, and efficient locomotion.