Time and duration problem from "Nihongo So-Matome N3 - Listening"


[One of the questions](https://i.stack.imgur.com/VEqIU.jpg) from _Nihongo So-
Matome N3 - Listening_ :

>
> 男【おとこ】の人【ひと】と女【おんな】の人【ひと】が話し【はなし】ています。男【おとこ】の人【ひと】は、明日【あす】何時【なんじ】ごろ家【いえ】を出ます【でます】か。
>
> 女【おんな】：明日【あした】の飛行機【ひこうき】、何時【なんじ】？  
>  男【おとこ】：えーと、１６時半【じはん】出発【しゅっぱつ】。  
>
> 女【おんな】：国際線【こくさいせん】だから、２時間【じかん】前【まえ】には着いて【ついて】おかないとね。えーと、空港【くうこう】までここから２時間【じかん】かかるとして・・・  
>  男【おとこ】：そんなにかからないよ。今【いま】、電車【でんしゃ】、速い【はやい】のがあるし。１時間半【じかんはん】あれば十分【じゅうぶん】だよ。
>
> 男【おとこ】の人【ひと】は、明日【あす】何時【なんじ】ごろ家【いえ】を出ます【でます】か。
>
> １ 午後【ごご】１時【じ】ごろ  
>  ２ 午後【ごご】１時半【じはん】ごろ  
>  ３ 午後【ごご】２時【じ】ごろ  
>  ４ 午後【ごご】２時半【じはん】ごろ

Can someone explain why the answer is 1?

In my opinion, 男 said that the plane will fly at 16.30 pm. And, he also
implied that it takes only 1 hour and a half to arrive at the airport. So I
think that they will leave their house at 15.00 pm. (although it's not in the
answer choices)




The woman also says ２時間前には着いておかないとね, "you need to get there 2 hours early". So
it's １４時半 (午後２時半) that is the goal for arrival at the airport, and it takes
１時間半 to travel to the airport, so that's the difference between the １６時半
airplane departure and the 午後１時ごろ house leaving time.




The woman also says ２時間前には着いておかないとね, "you need to get there 2 hours early". So
it's １４時半 (午後２時半) that is the goal for arrival at the airport, and it takes
１時間半 to travel to the airport, so that's the difference between the １６時半
airplane departure and the 午後１時ごろ house leaving time.

