Why would a young girl do that?

This morning, Bobo took the bus to work (it's been a while). She met this cute girl. Well she's rather cute. Pretty Young Thing really. As she was getting up the bus, she did something that really made Bobo wonder. It's something that Bobo won't do and she's really curious how many people would do the same. Try to answer Bobo if you can, will you?

Look at the picture below.

It's a Superbus with double decks and on the lower deck there are seats that face each other.

Blue seats are the empty seats while pink are occupied.

Occupier 1 is Bobo herself.

Occupier 2 is a lady dressed professionally. She looks about 20+ and is actually quite attractive with long hair and all. She's slim and fits well into her seat with more than enough space to spare. She doesn't have any odour nor overpowering fragrance.

Occupier 3 is a schoolgirl whom Bobo has met a few times. Honestly Bobo has always felt this girl to be a little strange. She's very grumpy and she's the sort who would stare straight at people. And even when you notice and stare back... she'd stare harder.

When the cute girl (about 17 or 18, dressed in street clothes) got up the bus... guess where she sat? She sat on Seat D. AND sat so near Occupier 3 that she nearly sat on one lap.

Bobo found that a little strange really. Bobo would have sat in A,B,E or G where there would be an empty seat between her and the next person.

Where would you sit?