<em>A megaphone used by a cheerleader can allow people on the opposite side of a field to hear her better because;</em>
D. Solid objects can change the direction of sound waves; megaphones allow users to determine the general direction of the sound.
<u>Determination of the general direction of the sound lessens its dispersion and thus, it reaches the observers at a higher intensity, hence it being louder.</u>
Explanation: Experience has taught us that the tone can help determine the direction of the sound waves. People riding a motorbike wearing a helmet, for example, often find it difficult to hear where an ambulance is coming from, as the helmet reduces the outer ear's ability to determine the tone of the sound.
When a person hears sounds of limited wavelengths, the head functions as a screen. If the sound comes from a direction to the right of the face, the head will prevent the sound waves from reaching the left ear. Deep base sounds, on the other hand, have a larger wavelength, and the head will not prevent the sound waves from reaching both ears.
Pollen is a very efficient way to colonize and reach further. It's believed that this adaptation is the main reason why land plants could colonize so many environments. The fact that pollen is little and easily transported also was very important.
