select
揀 centers on the act of choosing or selecting, often with a sense of careful discrimination.
揀 combines 扌 (hand) with 柬, which likely contributes the sound and the idea of separating or selecting. The exact historical development of 柬 is uncertain, but the character as a whole suggests picking out with the hand.
The hand radical 扌 beside 柬 suggests a hand carefully picking one item from a bundle or selection.
For カン, imagine a hand selecting a can from a shelf: can -> カン, and the hand picks the right one.