Answer the following question given this paragraph: 

Some invertebrates evolved a rigid rod along the length of their body. This rod is called a notochord. You can see the notochord in the tunicates in Figure below . The notochord gives the body support and shape. It also provides a place for muscles to attach. It can counterbalance the pull of the muscles when they contract. Animals with a notochord are called chordates. All of them are placed in Phylum Chordata. Some early chordates eventually evolved into vertebrates.


Q: A notochord has in common with what vertbrate structure?

 Choices:

- trichord

- rib cage

- rip chord

- spinal cord

A:
spinal cord
