"consider a gram-negative pathogen isolated from marine mammals. this pathogen is subjected to a series of tests and found to have the following characteristics:
a) oxidase-positive,
b) does not hydrolyze urea,
c) produces indole,
d) does not produce acetoin.

The pathogen is Pasteurella multicida.

Explanation:

Pastuerella multicida is a gram negative, non motile bacteria that is penicillin sensitive and belongs to the family pasteurellaceae. It is a common cause infection from dogs and cats bites.

Gram staining is a method use to distinguish and classify bacterial species into large groups which are either gram positive or gram negative.

Gram negative bacteria are bacteria that do not retain the crystal violet stain used in their gram staining while

Gram positive bacteria are bacteria that retain the crystal violet stain by their thick peptidoglycan cell wall found in them.