Final answer:
The fossil footprints at Laetoli show that the hominins had a nondivergent big toe, heel strike, and a well-developed arch in their feet; hence, the correct answer is D) all of these.
Step-by-step explanation:
The fossil footprints at Laetoli provide significant evidence for early hominin bipedality. These footprints, which are over 3.5 million years old, show clear bipedal characteristics that are remarkably similar to those of modern humans. Let's consider the features they depict:
- A) Nondivergent big toe: Like humans, the big toe is in line with the other toes, which helps in forward motion.
- B) Heel strike: This is the initial contact of the heel with the ground, indicative of a walking gait.
- C) Well-developed arch: The presence of an arch helps in absorbing shock and adding spring to the step.
All these features contribute to efficient bipedal walking, indicating that the answer to the student's question is D) all of these.