Answer:
C. 444 Ma
Step-by-step explanation:
The first plants that managed to colonize the land appeared around 470 million years ago, while the first arthropods on land appear i the fossil records around 450 million years ago, so we can say that around the period of 444 million years ago they were well established on land. The first arthropods that started to have terrestrial life were almost identical to those in water, with only minor changes that enabled them to breathe and move more easily. The first plants on land were non-vascular plants. They were small as they initially didn't had deep and well established roots.