A biennial weed is characterized by which of the following?

A biennial weed is typically characterized by its life cycle, which spans two years. During the first year, it primarily focuses on growth and development, establishing a robust vegetative structure through leaves and roots without flowering or producing seeds. This period allows the plant to store energy and nutrients, preparing for the next stage in its life cycle.

In the second year, the biennial weed shifts its energy towards reproduction. It flowers and produces seeds, completing its life cycle. This distinction between vegetative growth in the first year and reproductive efforts in the second year is what fundamentally defines biennial plants. Thus, the answer accurately reflects this two-year life cycle pattern observed in biennial weeds.