The correct options are
A Amphioxus
D Frog
Protochordates and vertebrates are chordates. All chordates have a notochord.
Protochordates possess a notochord at some stages during their lives. E.g., Balanoglossus, Herdmania, Amphioxus, etc.
In vertebrates, the notochord is replaced by a vertebral column during later stages of their life. E.g., Frog, fish, humans, etc.
Starfish ( Echinodermata) and snails ( Mollusca) are non-chordates.