What makes something living or nonliving?

The term living thing refers to things that are now or once were alive. A non-living thing is anything that was never alive. In order for something to be classified as living, it must grow and develop, use energy, reproduce, be made of cells, respond to its environment, and adapt.

answer: - b cells

explanation: -

so, the b cells mediate their action by identifying the antigens present on the surface of the pathogens and then producing antibodies in return to mediate its effect.

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.