The Answer is A: 1 hour
Explanation:
since they can drive 3/4 the distance in 3/4 hours, they can also drive 1/2 the distance in 1/2 hours and so on. If they want to visit the grandparent's house, they need to drive 4/4 the distance which is equivalent to 1 so it will take 1 hour for them to go to the house at the same rate.
A Tip From Me To You:
sometimes the question tries to trick you to make you overthink it so don't overthink it, try to just solve it simply.
Have a great day! <3