Analogy — Ink : Pen :: Blood : ? Pick the option that stands to “blood” as a conduit or carrier, analogous to how a pen carries or contains ink.

Introduction / Context:
“Ink : Pen” captures a container/conduit relationship: a pen holds and delivers ink. For blood, we need the bodily structure that contains and conducts it. Among the options, only one names the anatomical conduit for blood.

Given Data / Assumptions:

• Pen carries/dispenses ink.
• Blood is carried within vessels (arteries and veins).
• The option should be a conduit, not an event, role, or action.

Concept / Approach:
Preserve the carrier–content relation. In human anatomy, “vein” and “artery” are the principal conduits. Since only “vein” appears, it is the appropriate analogue for “pen” with respect to “blood.”

Step-by-Step Solution:

Verification / Alternative check:
Basic biology: veins return blood to the heart; arteries carry blood away. The presence of “vein” makes it the correct conduit counterpart.

Why Other Options Are Wrong:

• Donation — an act, not a vessel.
• Accident — an event.
• Doctor — a person/profession, not a carrier.

Common Pitfalls:
Selecting a contextually related term (doctor) instead of the structural carrier demanded by the analogy.

Final Answer:
Vein