California is home to the largest, tallest, and oldest trees on earth, all of which are

California is home to the largest, tallest, and oldest trees on earth, all of which are gymnosperms.
Gymnosperms are plants that have seeds and are usually coniferous trees. Given that those largest, tallest, and oldest trees are sequoias, this seems to be the correct answer.
Nonvascular plants are quite small. Seedless vascular plants is also incorrect, because sequoias have seeds. Angiosperms are flowers.