The correct answer is option 1, Lettuce.

Lettuce is not obtained from wild cabbage. Although lettuce belongs to the same family as cabbage, which is the Brassicaceae family, it is a different species. Lettuce is derived from Lactuca sativa, while wild cabbage is derived from Brassica oleracea.

Option 2, Broccoli, is derived from wild cabbage. It is a cultivar of Brassica oleracea, just like other vegetables such as cauliflower and Brussels sprouts. Broccoli is characterized by its dense heads and thick stalks.

Option 3, Kale, is also derived from wild cabbage. Kale is a leafy green vegetable that belongs to the same species as wild cabbage, Brassica oleracea. It is known for its curly or flat leaves and is often used in salads, soups, and stir-fries.

Option 4, Kohlrabi, is also obtained from wild cabbage. Kohlrabi is a cultivar of Brassica oleracea and is a unique vegetable that has a turnip-like swollen stem. It is commonly used in salads or cooked as a side dish.

Therefore, the only option that is not obtained from wild cabbage is Lettuce.