Answer: C. Steel
Explanation: When a sound wave travels through a solid body consisting
of an elastic material, the velocity of the wave is relatively
high. For instance, the velocity of a sound wave traveling
through steel (which is almost perfectly elastic) is about
5,060 meters per second. On the other hand, the velocity
of a sound wave traveling through an inelastic solid is
relatively low. So, for example, the velocity of a sound wave
traveling through lead (which is inelastic) is approximately
1,402 meters per second.
Mutualism is a long-term relationship where two organisms interact in such a way that both of them benefits from that relationship.
For example, there is a relationship between a bird called "oxpecker", and a rhino. While the bird eats the harmful bugs (eg. tick) on the rhino's skin and relieves its hunger; the rhino gets rid of the bugs that harm it.
