lapply returns NULL ?

Dear all,

I have a list of arrays :

foo<-list(A = c(1,3), B =c(1, 2), C = c(3, 1))

$A
[1] 1 3

$B
[1] 1 2

$C
[1] 3 1

$A
[1] 1 3

$B
[1] 1 2

$C
NULL

I don't want to list $C NULL in the output. How I can do that ?