To vary the sentence structure i would use "B. Have you noticed how hard she works?" as an answer. This is because the construction of A is the same as of the third sentence; C is the same; and D is similar to sentence one, based on the structure.
Answer:
A
Explanation:
Third person is like a narrator (Think the voice in a penguin documentary)
Few people can be seen
Some children are playing
Their father is reading the newspaper
Answer:
D) A population of moose living at the base of a volcano is nearly wiped out when the volcano erupts.
Explanation:
Genetic Drift is when the size of a population is severely reduced, or disappear from the population. Example D is the best example of that.
I hope I helped!