'DESCEND TO FL100, QNH 1013' instructs the pilot to:

Set QNH 1013 at FL100 and report

Maintain FL100 permanently

Descend to 10,000 ft on QNH 1013 immediately

Descend to FL100 and set altimeter to 1013 when passing transition level

Correct

Explanation

The pilot descends to FL100 and sets QNH 1013 when passing through the transition level to continue the descent on altitude.

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