Answer are C. shrubs and A. tall, mature trees.
Seed is a structure which is formed from mature ovule. Angiosperms and gymnosperms are the plant groups which produce seed. Shrubs are members of angiosperms. These are bushy and small to medium in size woody flowering plants, examples roses, jasmine etc. The seeds are develop inside an ovary of a carpel (female reproductive part of the flower). Algae, fungi and mosses do not produce seeds.
Climax community are the final stage of biotic succession attainable by a plant community in an area under the environmental conditions present at a particular time. For example, mature lived tree species.