Answer:
The correct options are;
A. [tex]-\dfrac{8}{3}  \ miles[/tex]
D.  [tex]2\dfrac{2}{3}  \ mile[/tex] below sea level
Step-by-step explanation:
The given parameters are; 
The distance Sasha travels down before a stop = -2/3 mile
The level at which Sasha starts to hike into the canyon = Sea level
Therefore, we have;
Her elevation at the fourth rest station = 4 × -2/3 mile = -8/3 miles
Therefore, we have;
-8/3 mile = [tex]2\dfrac{2}{3}  \ mile[/tex] below sea level
Therefore, the correct options are;
-8/3 mile and  [tex]2\dfrac{2}{3}  \ mile[/tex] below sea level.