Why would only one person getting sick from a new disease be considered an outbreak?

It's a new disease so no one can be sure of how fast it spreads, how it spreads, its symptoms, or anything else about it. It's an outbreak because nothing or not much is known about it.

i think the answer is b.

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave