Answer is 6.84 approx
reason:-
(2.78^2+6.25^2)^1/2=6.84 approx
This question involves the concepts of average speed, distance, and time.
The average speed of the family is "2.5 mi/hr".
<h3>AVERAGE SPEED</h3>
The average speed is defined as the ratio of the total distance covered with the total time taken to cover it.

where,
- s = distance covered = 2.5 miles
- t = total time taken = 1 hour
- v = average speed = ?
Therefore,

v = 2.5 mi/hr
Learn more about average speed here:
brainly.com/question/12322912
Increased by a factor of 4
Eras and then smaller periods based on geologic and biologic events that occurred during those times. According to geological time scale, there are six eras from the beginning some periods of few eras & then period is classified into smaller units called "epoch"
In short, Your Answer would be Option B
Hope this helps!