Zephyr agrees to mow his brother Zeke's lawn for free while Zeke recovers from a broken leg. Zeke tells Zephyr not to use the mower if its warning light turns on, but Zephyr ignores the warning. The engine overheats, ruining the lawnmower. Is Zephyr liable for the damage?
a. No. Zephyr was not Zeke's agent because he was not getting paid and therefore cannot be held liable.
b. Yes, because Zephyr's conduct was negligent.
c. Yes, because Zephyr's conduct was grossly negligent.
d. No, because gratuitous agents are never liable.