Answer:
The normal dorsiflexion range of motion for the tibio-calcaneal joint is 10-20 degrees, which is necessary for walking and other activities. Therefore, the correct multiple-choice option is (A).
Step-by-step explanation:
The normal range of motion for dorsiflexion (DF) at the tibio-calcaneal joint (TCJ) is generally considered to be approximately 10-20 degrees. This range allows for the proper function of the ankle and foot during activities such as walking, where dorsiflexion is necessary for the heel-to-toe transition.
The specified ranges, such as 30-40 degrees, 50-60 degrees, and 70-80 degrees, would be excessively high for this particular joint and are not considered to be within the normal functional range. Therefore, the correct multiple-choice option is (A).