Select the most appropriate meaning of the underlined idiom in the given sentence.
He's a past master at keeping his whereabouts secret, laying false trails.
1
One who is an expert
2
A former teacher
3
An incumbent teacher
4
Mastermind behind a plan
Select the most appropriate meaning of the underlined idiom in the given sentence.
He's a past master at keeping his whereabouts secret, laying false trails.