Transverse waves contain crests & troughs
while longitudinal waves contains compressions &rarefactions.
Yes, the pterosaurs is the ancestor of the bird.
An atom that gains a negative electron, it becomes a negative ion. If it loses an electron it becomes a positive ion. Some atoms lose electrons and become positive ions. Others gain electrons and become negative ions.
It would be d because you could get it again but it would be a different kind
