Instruction: Identify the assumptions that must hold for the statement to be valid, then choose the correct option. Statement: The discovery of exoplanets in habitable zones around distant stars has provided exciting prospects for the search for extraterrestrial life, yet the vast distances and technological limitations pose significant obstacles to direct exploration. Assumptions: I. Exoplanets located in habitable zones may have the potential to support life. II. Current technology is insufficient to directly explore exoplanets in habitable zones. III. Direct exploration of exoplanets will be unnecessary if we detect signs of life remotely.

Correct — A.
Rule: an assumption is what must be true for the statement to stand.

I holds: the discovery offers prospects for the search for extraterrestrial life only if such planets may be able to support life.

II holds: the statement names technological limitations as an obstacle, so today's technology is taken to fall short.

III fails: the statement does not need it. Its prospects and its obstacles stand whether or not remote detection would replace exploration.

I and II → option (a).

Why the others are wrong

• (b)
  Only II and III are implicit — II and III leaves out I, which the statement's hope of finding life depends on, and adds III, which the statement does not need.
• (c)
  Only I is implicit — Only I leaves out II, yet the statement names technological limitations as an obstacle to direct exploration, so it takes that shortfall for granted.
• (d)
  All assumptions are implicit — All three includes III, but the statement does not need it: the prospects and the obstacles stand whether or not remote detection would make exploration unnecessary.

An implicit assumption is an unstated premise the statement needs. A quick check is the negation test: deny the assumption, and if the statement no longer makes sense, it was assumed.

Deny I, so habitable-zone planets cannot support life, and the exciting prospects vanish. Deny II, so technology is enough, and the obstacle disappears. Deny III and the statement is unchanged: it makes no claim about what remote detection would do.

Key facts

• An implicit assumption is an unstated premise that the statement depends on.
• Negation test: deny the assumption, and if the statement no longer makes sense, it is implicit.
• A premise the statement does not need, however plausible, is not implicit.

Common traps

• Rejecting II because it repeats the statement instead of hiding behind it
• Accepting III because it sounds reasonable, without asking whether the statement needs it

No directly related past PYQ was found.