A list of twenty intergers

[SagarS393]

I have doubt on below question.
A list contains twenty integers, not necessarily distinct. Does the list contain at least two consecutive integers?

(1) If any single value in the list is increased by 1, the number of different values in the list does not change.

(2) At least one value occurs more than once in the list.

Manhattan answer is C. But I think the answer shall be E

I considered number set as (1, 1, 2, 10, 15) - 4 different numbers
In above set if I increase any number by 1, I will be satisfying both conditions (1) and (2)
Now, adding 1 to any number present in set will give me at least 2 consecutive numbers except if I increase 2 by 1 and make it 3.

(1, 1, 3, 10, 15) - 4 different numbers but no consecutive numbers are acquired.

Could any one please help me to clear my doubt?

Thanks,
Sagar Sonawane

[RonPurewal]

(1, 1, 3, 10, 15) doesn't satisfy statement #1. if you increase one of the 1's by 1, you get (1, 2, 3, 10, 15) which now has five distinct values whereas you started with just four.