Exam #2: the traps change

Exam #2 changes the traps, not the topics. Where Exam #1 tested whether you knew the mechanism, this one tests whether you hold it under misdirection:

• The dead-variable trap: a plausible variable is updated and never read — options built on it are wrong.
• The near-miss clause: the spec says "at least 3"; the code and three options say "> 3". Only one option honors the clause.
• The order trap: two mutations commute in the example but not in general; the options include the commuting reading.
• The mirror trap: a correct-looking symmetric pairing (i ↔ length - i) applied where the data is NOT symmetric.

Strategy is unchanged — triage, banking, the no-blanks rule — but your expectation should shift: in Exam #2, the first answer that "looks right" is disproportionately the trap. Verification beats recognition one notch harder here.