Final answer:
In Greek mythology, it was Achilles' mother, Thetis, who anointed him with ambrosia, but within Homer's Iliad, the act of filling him with ambrosia. Athena ,option b, is known for aiding Achilles but does not directly match the request.
Step-by-step explanation:
The student is asking about a detail from the literary masterpiece, The Iliad, which depicts the epic tales of the Trojan War. Specifically, they're inquiring about the character who ordered Achilles to be filled with ambrosia to keep him strong for battle.
However, it is known from Greek mythology that ambrosia was often associated with the gods and their ability to confer strength and immortality.
In general Greek mythology, and not specifically in Book 19 of the Iliad, it was Achilles' mother, Thetis, who anointed him with ambrosia.
Among the options provided, Athena is known to have aided and favored Achilles throughout the poem, including bestowing gifts upon him, but the act of filling him with ambrosia to keep him strong does not directly correspond to a single mentioned instance within the epic.