What is the correct preposition in the following sentences?

Question

1. Adventure is the main factor of increasing tourism.

2. Adventure is the main factor for increasing tourism.

And why?

Answer 1

for

Answer 2

1 sounds better

of makes it sound in the present whereas for makes it sound in the future, something yet to come.

Answer 3

The first one.  However, I think you've gotta go with "in".  Factors are pieces of the whole.  

Answer 4

Personally, I would use "in" but if it's a choice between the two, I would use "for".

Answer 5

number 2 because it is the main factor for increasing tourisim, it is grammatically correct and adventure isnt the main thing to increase tourism as number one suggest. number 2 suggests it would help.