What is the cladistic approach to classification?

The cladistic approach groups taxa based on shared derived characteristics (synapomorphies) that are unique to that group.
The cladistic approach aims to reconstruct evolutionary relationships and produce a phylogenetic tree.
The cladistic approach does not take into account convergent evolution or analogous structures.
a) The cladistic approach groups taxa based on shared ancestral characteristics (plesiomorphies) that are unique to that group.
b) The cladistic approach groups taxa based on shared characteristics, regardless of whether they are ancestral or derived.
c) The cladistic approach groups taxa based on shared derived characteristics (synapomorphies) that are unique to that group, and aims to reconstruct evolutionary relationships and produce a phylogenetic tree.