Why does hillary include this information in the final assault

The oxygen bottles reveal that the climb up Mount Everest is so difficult that climbers cannot carry their equipment back down the mountain.

Explanation:

The partially used bottles imply that climbers can reach high altitudes without the use of oxygen.

since it is asking for her reaction to elnora's trouble at school you can rule out any answers with a positive response (b). then you can rule out (d), this is because it does not show the mother's reaction but the daughter's response. that leaves you with two options (a) and (c), by looking at the options you can rule out (c) because it isn't referring back to elnora's issues at school.