Final answer:
Option (A), The allusion 'It was too late to turn back... and had left no crumbs behind' refers to 'Hansel and Gretel', where the characters cannot retrace their steps because the breadcrumbs they left as a trail are gone.
Step-by-step explanation:
The phrase “It was too late to turn back, for we had both wandered out too far into a net of expectations and had left no crumbs behind” is an allusion to A) Hansel and Gretel. This fairy tale features two siblings who leave a trail of breadcrumbs behind as they venture into a forest to find their way back home.
However, the birds eat the crumbs, and they are unable to retrace their path, leading them into further trouble. The phrase suggests a point of no return, where the characters cannot backtrack due to the decisions they've made and the expectations set upon them.