Consider the following projects:

A: c$0=-1000,$c$1=1000,$c$2=0,$c$3=0,$c$4=0,$c$5=0$

B: c$0=-2000,$c$1=1000,$c$2=1000,$c$3=4000,$ c$4=1000,$c$5=1000$

C: c$0=-3000,$c$1=1000,$c$2=1000,$c$3=0,$c$4=1000,$c$5=1000$

$1.$ If opportunity cost of capital is $10$ percent, which projects have a positive NPV$?$

$2.$ Calculate the payback period for each project

$3.$ Which project$($s$)$ would a firm using the payback rule accept if the cutoff period were $3$ years?