Here's why:

* Shared Evolutionary History: Charophytes are a group of green algae that share a common ancestor with land plants. This evolutionary connection is supported by numerous similarities in their:

* Cellular Structure: Both charophytes and land plants have cell walls made of cellulose, chloroplasts containing chlorophyll a and b, and store food as starch.

* Reproductive Processes: Both groups have similar reproductive mechanisms, including the presence of flagellated sperm and the formation of zygotes.

* Molecular Evidence: Genetic analysis has confirmed the close relationship between charophytes and land plants, placing them in the same clade (a group of organisms sharing a common ancestor).

While other green algae, like chlorophytes, also share some similarities with land plants, charophytes are considered the most closely related.