The diagram shows the life cycle of a fern. HELP ASAP!!!!

What does stage 3 show?
A) A mature spore-producing fern plant has fonds and produces spores.
B) A spore grows into a mature gamete-producing plant.
C) A zygote forms when a sperm fertilizes an egg cell
D) A gamete-producing fern plant is flat and shaped like a heart.