Trench foot is a condition that occurs due to prolonged exposure to damp and unsanitary conditions. It commonly affected soldiers during World War I who spent long periods in wet trenches. The condition is caused by a combination of cold, wet conditions and poor foot hygiene. Symptoms include numbness, swelling, and blisters. If left untreated, it can lead to tissue damage and infection. Therefore, trench foot is the correct answer in this case.