Which of the following plants reproduces by underground bulbs and above-ground bulblets?

Wild garlic is the correct answer because it is known for its unique reproductive strategy that involves the production of both underground bulbs and above-ground bulblets.

Underground bulbs are specialized storage organs that help the plant survive adverse conditions and can produce new shoots and roots. Above-ground bulblets are small bulbs that develop on the mother plant, providing a means for vegetative reproduction, allowing the plant to spread and establish in new areas efficiently. This characteristic of wild garlic reflects its adaptability and resilience in various environments.

The other choices do not exhibit this specific reproductive method. Wild onion also produces underground bulbs, but it does not typically produce bulblets above ground. Wild violet reproduces mainly through seeds and vegetative means (such as runners) rather than bulbs. Crabgrass is a type of annual grass that reproduces through seeds rather than bulbs or bulblets. This understanding of the reproductive strategies of these plants is crucial for effective management and control in pest management practices.