Answer:
Semiconservative; old
Step-by-step explanation:
When DNA is replicated, one original parent strand is kept as a template, while a new one is formed by using the original parent strand as a template. This yields one new parent strand, and one new "daughter" strand that is complementary. This is known as the semi-conservative model of DNA replication.
Note: DNA cannot be replicated from thin air. A template of some sort has to be used, and it is always from a parent strand. This ensures very minimally, if at all, errors in DNA replication such as mutations.