Statement–Courses of Action (border health & travel control): A large number of travellers arriving in India from country X have tested positive for a highly lethal viral disease; to contain importation risk and protect public health, which course(s) of action logically follow—(I) impose a complete entry ban on all persons coming from country X, including Indian citizens settled there, or (II) immediately set up detection and screening centres at all airports and seaports to identify infected travellers and quarantine those who test positive?

Given data

• Many visitors from country X are testing positive for a deadly viral disease upon arrival in India.
• Proposed actions: (I) a complete ban on all incoming persons from country X, including Indian nationals living there; (II) set up detection/screening centres at all ports of entry to identify and quarantine positives.

Concept/Approach (proportional, feasible, rights-compatible public health response)
Choose the action(s) that directly address importation risk, are implementable without adding unstated assumptions, and do not unnecessarily violate rights or international movement norms.

Step 1: Assess Course I (total entry ban, even on citizens)
A blanket ban is an extreme, rights-intrusive measure (especially for citizens) and not logically necessary given less-restrictive, effective alternatives stated in the problem.

Step 2: Assess Course II (universal screening + quarantine)
Screening at all ports directly targets the risk pathway, enables case finding, isolation, and contact tracing, and is proportionate to the stated threat.

Verification/Alternative
If effective screening and quarantine exist, importation risk falls without a total ban; therefore Course II alone logically follows from the statement.

Common pitfalls
Equating "serious threat" with "total ban"; ignoring less-restrictive controls explicitly available in the options.

Final Answer
Only II follows.