The correct answer is D. sturdy.
Sturdy shoes are important for walking in the hills because they provide support and protection for your feet. They should be made of durable materials that can withstand the elements and rough terrain. Sturdy shoes also help to prevent injuries, such as blisters and sprained ankles.
Good shoes are also important for walking in the hills, but they are not as important as sturdy shoes. Good shoes should be comfortable and fit well. They should also be made of materials that will keep your feet dry and warm.
Comfortable shoes are important for any activity, but they are not as important for walking in the hills as sturdy shoes. Comfortable shoes should fit well and not cause any pain or discomfort.
Satisfactory shoes are not good enough for walking in the hills. They are not sturdy enough to provide the support and protection that you need. They are also not comfortable enough to wear for long periods of time.
Therefore, the correct answer is D. sturdy.