I have trouble with article [closed]

I have just done an English exercise and it's about error correction: "You will remove one word which is unnecessary in each example." Here is the sentence which I meet the unnecessary word:

Thanks to cheap air travel, for many people the world has grown significantly smaller over the last decade, but to vegetarians, the planet can still seem frustratingly limited. For millions of us who don't eat meat, getting the right food while on the holiday can be a key factor when choosing our destination.

The key told me that the unnecessary word is the but I don't know why? Could anyone explain it to me, please?

This is the unnecessary the:

"Thanks to cheap air travel, for many people the world has grown significantly smaller over the last decade, but to vegetarians, the planet can still seem frustratingly limited. For millions of us who don't eat meat, getting the right food while on THE holiday can be a key factor when choosing our destination."