What is a key characteristic of a plant that is classified as an annual?

A plant classified as an annual is characterized by its ability to complete its entire life cycle within one year or less. This includes germination, growth, flowering, seed production, and the eventual death of the plant. Annuals typically sprout from seed, grow rapidly under favorable conditions, and produce their seeds within the same growing season. This rapid life cycle allows them to take advantage of optimal environmental conditions, which is particularly advantageous in temperate regions where seasonal climatic changes occur.

Other options do not accurately describe annual plants. For instance, a plant that lives for two years would be classified as a biennial, while flowering every year does not strictly adhere to the annual growth cycle, as some perennials may also flower each year. Additionally, plants that remain dormant for a season are typically categorized as perennials or biennials, rather than being defined as annuals. Thus, identifying the life cycle completion within a single year as the defining feature underscores the essence of what makes a plant an annual.