Which is known as Dead man's finger?

Answer: Option A

Xylaria polymorpha is known as Dead man's finger.
Xylaria polymorpha, commonly known as dead man's fingers, is a saprobic fungus.
It is a common inhabitant of forest and woodland areas, usually growing from the bases of rotting or injured tree stumps and decaying wood.
It has also been known to colonize substrates like woody legume pods, petioles and herbaceous stems.