

Yes we can. When these two charged bodies are hanging we need to observe their interaction. It is mentioned that charged body A id positively charged. Now if the charged body is getting freely attracted to the body A, that means it carries the opposite charge. That is the charged body B is then negatively charged.
On the other hand, if the body B is repelled by the body A, that means B is carrying the same charge as A. In that case, B is positively charged as well.
