Answer:
B) metaphor
Step-by-step explanation:
A metaphor is a figure of speech that refers to another thing by not directly naming it, but rather using a word or phrase. There is usually a similarity between the word or a phrase used and the idea that is behind it.
When excerpt talks about "different blueprints" for achieving Alexander's happiness, it uses the metaphor of a blueprint instead of direct words that could be idea, plan, concept.
Blueprint is used as a metaphor for an outline of plans for the future that Alexander should take in order to achieve the feeling of happiness.
As blueprint is a form of technical drawing presented on the light-sensitive sheet that drafts the plan of a certain project, it is a good metaphor for the sketched idea each character had in their mind.