Knight's move cap

Knight's move cap  

is a knight's move cap against . Compared to the ordinary cap at a this is more forceful. That doesn't imply that it is better; but this is one of the standard ideas of reduction play.

Passive?  

in reply is good for security; but in some contexts it will be a little too submissive.

Tenuki  

Simply ignoring White's play invites , which is quite severe. One advantage the knight's move cap has is that this follow-up is stronger than in the case of the cap.

Strong resistance  

Black should consider fighting harder with the contact play and cross-cut . Now there will be a tough fight, and ladder relationships can be important.

White tries to settle  

Therefore is an option: this warikomi play makes it quite hard for Black to decide between a and b next.