Concept:Weeds are hardy plants that survive harsh conditions and spread quickly through efficient seed production.
Explanation:Weeds are generally resistant to trampling because they grow firmly in disturbed soils.
They produce numerous seeds to increase their chance of survival and spread.
Weed seeds usually have a long period of viability, meaning they can remain alive in the soil for many years.
They also show an aggressive growth habit, quickly competing with crops for space and nutrients.
Thus, having seeds with a short period of viability is not a typical weed characteristic.
Answer:C. seeds have short period of viability