Why are the weapons of beowulf's warriors ineffective against grendel?

a. grendel cannot be harmed by another human
b. grendel puts magic spels on the weapons so they can't hurt him
c. the geats do not have the same weapons as the danes
d. the warriors are to scared to use them effectively

Which excerpt from chapter 3 of the strange case of dr. jekyll and mr. hyde illustrates a character vs. character conflict? hosts loved to detain the dry lawyer, when the light-hearted and loose-tongued had already their foot on the threshold; they liked to sit a while in his unobtrusive company. the large handsome face of dr. jekyll grew pale to the very lips, and there came a blackness about his eyes. “i do not care to hear more,” said he. “this is a matter i thought we had agreed to drop.” “my good utterson,” said the doctor, “this is very good of you, this is downright good of you, and i cannot find words to you in. i believe you fully; i would trust you before any man alive, ay, before myself.” but i do sincerely take a great, a very great interest in that young man; and if i am taken away, utterson, i wish you to promise me that you will bear with him and get his rights for him.”