The correct answer is B, widespread pollution. If you look closely, you can see that the other answers are not problems at all, but benefits! :)
The gravitational pull of the Sun the interstellar dust attracting heat away from the protosun the process of nuclear fusion the nebular cloud condensing.
I believe it goes as the following::
1) Waves transfer energy without moving particles
2) The two types of waves are longitudinal and transverse waves OR The two types of waves are mechanical and electromagnetic waves. Both are applicable and should be correct!
We know,
Speed = Frequency * Wavelength
Speed = 3 * 0.1 m/s [hertz = 1/sec.]
So, your final answer is 0.3 m/s
Hope this helps!!
