Statement: “For the third time this week, IGI Airport was put on full alert after Air India received an anonymous message that two terrorists with explosives were on the Mumbai–Delhi–Hong Kong flight,” says an airport authority.\nAssumptions I–III:\nI. The anonymous message is unlikely to be a hoax.\nII. The anonymous message is likely to be a hoax.\nIII. Alertness might help reduce the menace.\nChoose the option that correctly identifies the implicit assumption(s).

Introduction / Context:
Security responses to anonymous threats must balance false positives vs. missed threats. Regardless of belief about hoax likelihood, the recurring action (full alert) presupposes that heightened alertness is useful.

Given Data / Assumptions:

• I. Threat is probably genuine.
• II. Threat is probably a hoax.
• III. Going on full alert helps mitigate risk.

Concept / Approach:
The decision to go on alert can be justified if authorities think the threat might be real (aligns with I) or even if they think it is likely a hoax but choose caution (aligns with II). In either case, the utility of alertness (III) is necessary.

Step-by-Step Solution:
1) The action is sensible if authorities deem the message credible (I) — then alertness is prudent.2) Alternatively, even with hoax suspicion (II), standard protocol may demand alertness out of caution.3) In both scenarios, III is essential: alertness reduces potential harm.

Verification / Alternative check:
Without III, full alerts would be pointless regardless of hoax beliefs. Hence the correct pattern is “Either I or II, and III.”

Why Other Options Are Wrong:
Only I and III / Only II and III: each privileges one belief; the statement structure allows either belief combined with III. Only III: omits the threat-belief dimension guiding action.

Common Pitfalls:
Thinking authorities must commit to one view of credibility; in practice, protocols trigger alertness under uncertainty.

Final Answer:
Either I or II and III.