Differant is spelled different
practical
Even though Grendel seems as though he's being harsh by eating the exile, he is actually being practical. He says he tries to do things that are more considerate like befriending or ignoring him. However, since the exiles were treacherous, eating them is the most practical solution.
Based on the given scenario above, the answer would be option B. A secondary source. It is a secondary source since it is already seen in the magazines or printed articles and not directly from the person him/herself. Hope this answers your question.
I belive that the answer is d.molecules