Natural Selection, unless you were born in a lab which would be unnatural/artificial, and not too likely with today's technology. (Maybe one day.)
You should ask your teacher to be sure, but I think that you teacher meant like the mode of transmission.... Like genetically inherited and such.
Answer:
grow longer
Explanation:
In a long bone, the epiphyseal is the growing region. In young bones, bone formation occurs in a layer of hyaline cartilage. The epiphyseal plate forms cartilage on the epiphyseal end. Cartilage is calcified on the diaphyseal side, and the diaphysis lengthens.
They have very sharp teeth to cut through their prey, or try to escape if they are trapped
Their bodies are very narrow, enabling them to be very quick and nimble, it also enables them to hide it tight spaces
Their teeth also enables them to escape a fishermen's line ( I'm a fishermen and I've lost many barracuda due to those teeth.)
I hope this helped