Problem Solving

Questio is of the type:
If a,b,c are 3 consecutive nos and a,b,c are +ve and a < b < c then blah blah blah....

OG says the following in explanation to this question:
If 3 numbers a,b,c are +ve and a < b < c
then we can conclude that b = a + 1 and c = a + 2

My question why?

We can have something like
2,4,6
these are three consecutive even (+ ve) nos and 2 < 4 < 6
however 4 is not 2 + 1
and 6 is not 2 + 2

am i missing something ? i thought consecutive nos need not always be of the form 2,3,4,5...
we can have consecutive even nos,consecutive prime nos, consecutive odd nos etc...

aren't consecutive nos. supposed to mean necessarily, nos. that come one after the other? 1,2,3...

If the question states " consecutive integers" it necessarily means the no. which follow each other ( eg: 1,2,3,4,6....)
For GMAT, if they want us to consider consecutive even or odd integers, they would state that in the question, if they don't we assume it as just consecutive integers...

hmmm i guess we use nos one after the other for consecutive nos unless specified otherwise.
thanks Sid !