when something goes missing

so lets say there is a room.
with only two people, A and B
and then and extra person comes along, C. who is B's friend but does not know much of A

after awhile A realizes something is missing, item D
the reason is a mystery, no one has any idea where it disappeared to
it could have been misplaced by A himself and then forgotten,
it could have been moved by B or C
it could have been taken by B or C
it could have been taken by neither any of them, maybe someone else, E

so A ask B where it is,
B answer's "i genuinely have no idea"
"but i'll ask C"

B: "have you seen item D?"
C: "nope"

C: "are you saying i took it?"

so tadaa.. cool scenario... what to do now?

it might seem like B was implying that C took it.
but B has no intention what so ever to imply C took it
it just 'seemed' like it

it is just necessary for B to ask C, just as how he was asked by A
its like... curtsy.. xD or.. 'just-following-procedures'

but if C denies he took it, and he is telling the truth,
then were could item D magically have gone to?

A has to trust B
while B has to trust C

A can trust C directly but it is hard..

oh gosh.. God you know where item D is!