Explanation:

option 4

• Weeds causes health problems for human beings such as lung irritation, increased heart rate.
• A chemical analysis of weeds proves that there are many chemical compounds present, are may be useful for treatment of many diseases.
• Small species of Parthenium, Amaranthus, Argemone, Cynodon, Cyprus, Mimosa and Oxalis easily found in our garden and roadside, are having many medicinal values.
• Weeds give us clues to the health of our soil in our lawns, landscapes, gardens and pastures.