Chile's LAN Airlines had confirmed an/the order for 25 jets

[Glizdka]

This comes from Market Leader Intermediate - Progress Test 2.

Complete the text. Use a, an, the or zero article.

Shares in the aerospaceand defence group, EADS rose by_______________(16) 2 per cent to €29.89 on_______________(17) announcement that Chile’s LAN Airlineshad confirmed _______________(18) order for 25 jets from the European aircraftmanufacturer Airbus, _______________(19) joint companyowned by EADS andBAE Systems of_______________(20) UK.

The answer key provided states that the answers are:
16 - no article
17 - an
18 - an
19 - a
20 - the

My question is about gap 17. In my opinion, it sounds like a pice of writing that refers to a major event, and I see no problem with using the in gap 17. In other words, I think that...

Shares in the aerospace and defence group, EADS rose by________no article_______(16) 2 per cent to €29.89 on_______the________(17) announcement that Chile’s LAN Airlineshad confirmed _______an________(18) order for 25 jets from the European aircraftmanufacturer Airbus, ________a_______(19) joint companyowned by EADS and BAE Systems of_______the________(20) UK.

...is also fine. What do you think?

 

[GoesStation]

I agree. Both articles are possible.

 

[jutfrank]

I read it like this:

16) no article
17) the
18) an
19) a
20) the