Step 1: Observing the walk cycle progression.
Frames 1, 2, and 3 show the body leaning forward with the left leg preparing to move backward and the right leg preparing to lift. Frame 5 shows the next major pose after the passing position. Therefore frame 4 must be the *passing* pose where one leg crosses the other.
Step 2: Matching the correct passing pose.
Option C shows the correct body posture:
- Weight shifted to the supporting leg,
- Opposite leg swinging forward,
- Arms transitioning between forward and backward motion.
This matches the natural movement between frames 3 and 5.
Options A, B, and D show poses that are either too early or too late in the walk sequence.
Step 3: Conclusion.
Thus, the missing frame 4 is best represented by Option C.