Ella rode 16 miles in 4 hours
Since she rides at constant speed, her speed will be 1miles/4hours for as long as the ride takes, option C is not a valid option.
Now using cross multiplication we can determine the unit ratio, i.e. her speed per hour
4h ___16miles
1h____xmiles
She drives 4miles/hour → Option D. is equivalent.
Finally multiply the speed per hour by 6 to determine the equivalecy
She will drive 24 miles in 6 hours, option A is also equivalent.
The correct options are A and D