"The pizza is delicious, and they are eating all of it."
Translation:La pico estas bongusta, kaj ili manĝas ĉiom.
It's not needed, but it should be accepted. In the "Complete Grammar of Esperanto", you can see those examples of the usage of ĉiom :
THE DISTRIBUTIVE ADVERB ĈIOM.
The distributive adverb of quantity, related to the distributive pronoun ĉiu, is ĉiom, every quantity, the whole, all:
Li prenis multe da sukero, sed ne ĉiom da ĝi , he took a great deal of sugar, but not all of it.
Li elprenis ĉiom de la teo el la teujo, he took all of the tea out of the tea caddy.
AlixB. and frodetb have the same question I have.
Two sentences previous to "The pizza is delicious, and they are eating all of it" there was a sentence that had the specific "ĉiom da ĝi" marked correct. Then this sentence got marked wrong because I wrote "ĉiom da ĝi". What's up with that?