An impending war is evident because:
a. Young Fortinbras wants revenge
b. Denmark king wants his territory back
c. Hamlet killed young Fortinbras and took over his land
d. Numerous omens are evident
i choose B, is that correct?
No, not B.
Claudius was Denmark's king at this point, and he already had control of his own land.
http://nfs.sparknotes.com/hamlet/
Read Act I, Scene 1, starting about page 5 and onward.