The question is about choosing a phrase that softens the impact of a tragic event. 'A manageable crisis' suggests that the situation, although serious, can be dealt with effectively, which fits the advice to make the best of life. 'A devastating disaster' and 'A serious mishap' both maintain a negative tone, and 'A minor setback' downplays the severity of the event too much, which is not appropriate for a fire described as a 'terrible tragedy'.