Final answer:
The correct statement is that all synapomorphies are derived traits, meaning these traits are inherited from an ancestor and used to define clades in systematics.
Step-by-step explanation:
The statement about systematics that is true is that "all synapomorphies are derived traits." Synapomorphies are traits that are present in an ancestral species and are passed down to its descendants, making them derived traits within those descendant species. These are homologous traits that are used in cladistics to define clades, which are groups of organisms that descended from a single ancestor and exhibit those particular synapomorphic traits. On the other hand, homoplasies, or analogies, arise when species display characteristics that are similar due to convergent evolution but not due to the same evolutionary path. Therefore, the statements about all derived traits being synapomorphies or all homoplastic traits being due to convergent evolution are false, and it's also not true that all homologous traits are homoplasies or that all homoplasies are homologous traits.