The correct answer is Option A.
In the given sentence, Mike and Sarah take their children 'together' for the trip.
So we are to identify the word that correctly expresses the meaning of 'together'.
Option B- 'Aloud' means at a higher volume of speech.
Option C- 'Anew' means afresh or from the beginning.
Option D- 'Below' means beneath something.
None of these 3 options mean being together, hence are incorrect.
Option A- 'Along' means together. Mike and Sarah take their children with them. They go together.
Therefore Option A is the correct answer.