The correct option is (b).
Explanation
Weeds are unwanted plants that grow naturally alongside cultivated crops. They are characterized by their ability to grow rapidly and persist in agricultural fields, often acting as invasive species that disrupt the development of the primary crop.
Statement-wise Analysis
- Statement 1 is Incorrect: Xanthium (commonly known as Cocklebur) and Parthenium (commonly known as Carrot grass) are common examples of weeds, not beneficial crops. They are often invasive and can cause ecological damage as well as health issues, such as allergies, in humans and animals.
- Statement 2 is Correct: Weeds compete aggressively with crop plants for essential resources, including soil nutrients, water, physical space, and sunlight. Consequently, the presence of weeds limits the availability of these resources for the cultivated plants, leading to reduced growth and yield.
- Statement 3 is Incorrect: Weeds do not enhance nutrient absorption by crop plants; on the contrary, they deplete the soil of nutrients. By absorbing a significant portion of available minerals and water, they deprive the crop plants, thereby stunting their growth.
Key Takeaway: Weeds are undesirable plants (e.g., Parthenium, Xanthium) that negatively impact agricultural productivity by competing with crops for light, space, water, and nutrients.