Cuscuta, commonly known as dodder, is a parasitic plant that belongs to the family Convolvulaceae. It lacks chlorophyll and therefore is unable to produce its own food through photosynthesis like other plants. Instead, it relies on other plants for nutrients and water.

The correct answer is option 2: complete stem parasite. Cuscuta wraps its thin, thread-like stems around the host plant`s stems, penetrating its tissues to extract nutrients and water. It forms haustoria, specialized structures that connect to the host plant`s vascular system, allowing it to obtain nourishment directly from the host.

Although there are partial stem parasites and complete root parasites in the plant kingdom, Cuscuta specifically falls under the category of complete stem parasite as it primarily relies on the host plant`s stems for survival.