Which of the following items is not an essential item to carry in the rucksack while climbing a mountain?

Climbing a mountain is very difficult because of the scarcity of oxygen at such high altitudes. So it's very important to determine the items of extreme importance that need to be carried in rucksacks, without which mountaineers cannot successfully ascend the mountain; unnecessary items might slow their upward journey. The items presented as options A, B and C, torch, glucose (for energy) and windcheater (it is a wind-resistant jacket) are all crucial items that need to be carried. So option D is correct.