duration of call/put option

CFA Level II
#1

I am having a hard time understanding why the duration of a call option is positve and that of a put option is negative. Would you someone explain why? Thanks!

#2

By duration, you mean rho, yes? See: http://www.analystforum.com/phorums/read.php?1,578224,578292#msg-578292

#3

Thanks!