Explanation:

A & D

2, 4-D is a weedicide. 2,4-Dichlorophenoxyacetic acid  is a common systemic herbicide used in the control of broadleaf weeds. It is a synthetic auxin (plant hormone) and one of the most widely used herbicides in the world. 2,4-D is a possible carcinogen per WHO.
2,4-D was one of the ingredients in Agent Orange, a herbicide widely used during the Vietnam War. 2,4-D is primarily used as a selective herbicide which kills many terrestrial and aquatic broadleaf weeds, but not grasses. It acts by mimicking the action of the plant growth hormone auxin, which results in uncontrolled growth and eventually death in susceptible plants.
Weed is a wild plant growing where it is not wanted and in competition with cultivated plants. Weedicide is the chemical which kills weeds.