How does cladistics us understand phylogeny?

Gregor mendel was the first scientist to use statistics to analyze scientific data before mandel's experiments, scientists believed that organisms acquired traits from their environment and pass them on to their offspring after mendel's discoveries were accepted scientists realized that traits passed to offspring were the result of genes being passed from parent to his parents this is an example of

Adigestive system that is a series of tubes beginning at the mouth and ending at the anus is a digestive system.

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating