Please help me on the first one (highlighted)

Change in water source

Explanation:

officials from Flint, Michigan switched the city's water supply to the Flint River as a cost-cutting measure for the struggling city, and they unwittingly introduced lead-poisoned water into homes.

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

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