Why is it duż"e"? I thought it should by duż"y" because pomidor is masculine.
Duże is neu singular, and all plural but masc personal. Masc personal is duzi.
Wiktionary says that the plural masculine nominative form of duży is also duży. In addition, "tamte" is used for neuter nouns. I think there is a mistake and that "pomidor" is neuter, not masculine like we learned earlier.
It's difficult ;) In Polish you have three gendrers (masculine, feminine and neuter) in singular and two genders in plural (masculine personal and non-masculine-personal).
Pomidor is masculine (ten pomidor) so in singular it's "duży pomidor". When you have some tomatoes, they become non-masculine-personal gender (te pomidory) and than you have "duże pomidory".
"these" = "te" or "ci", "those" = "tamte" or "tamci".
The first options are for not masculine-personal plural, the second are for masculine personal plural (almost only 'a group of people including at least one man').
'those' is the right answer, 'the' was accepted, but it shouldn't be. It is acceptable for "te" (this), but not for "tamte".