Question

Which of the following pairs of ideas could be combined into a compound sentence? A.We watched the news on television. The girls walked quickly to school B. The street lights were dim. The play was a success. C. The weather had changed. The house seemed deserted. D. The days became longer. The children could play outside later.

Answer 1

First we need to find out which sentences makes sense. 
A is not related so is b, and c

so therefore your answer is D. It's related to each othere

 It is assumed here that children should be safe, so when they play outside, it should be daylight, and if the daylight is longer, they can also play outside longer than usually.

Answer 2

You can combine sentences with related ideas, so D. The days became longer. The children could play outside later.