thanks Brent ! my answer is E as well:
ALSO PLEASE LET ME KNOW : is ZERO positive? I think ZERO is neither positive nor negative.Please correct me if I am wrong.

Also consider the number 30

so Product < Sum
Hence E....Your thoughts on this please...thanks so much

But the official explanation from MANHATTAN suggests otherwise.
[spoiler]
N is a two-digit even integer. The tens digit can be anything except for 0. The units digit has to be 0, 2, 4, 6, or 8.

(1) NOT SUFFICIENT: Consider the values of N that can satisfy this statement. If the units digit is zero, then the product will always be zero; this will always be less than the sum of the digits.

For example, N could be 10, in which case the product of the digits is less than the sum of the digits. In this case, the answer to the question "is N < 20?" is yes. Alternatively, N could be 20, in which case the product of the digits is less than the sum of the digits. In this case, the answer to the question "is N < 20?" is no.

(2) NOT SUFFICIENT: If the product is positive, then the units digit can't be zero. In this case, N could be 12 and the answer to the question is yes. Alternatively, N could be 22 and the answer to the question is no.

(1) AND (2) SUFFICIENT: Statement 2 indicates that the units digit cannot be 0. All of the cases in statement 1, then, where the units digit is 0 must now be disregarded.

N could still be 12. The product, 2, is smaller than the sum, 3. In this case, the answer to the question is yes.

Could N be 22 or greater? If N is 22, then the product, 4, is equal to the sum, 4. You can't choose N = 22, then (remember that only numbers that make both statements true can be chosen). Are there any other possibilities greater than 22 that are valid?

If N = 24, then the product is 8 and the sum is 6; this doesn't fit statement 1. If N = 26, then the product is 12 and the sum is only 8; this also doesn't fit statement 1 (and is, in fact, even further away from what you want!). If N = 32, then the product is 6 and the sum is only 5; if N = 34, then the product is 12 and the sum is only 7. The higher you go, the larger the product gets compared to the sum. In other words, no larger number will have a product that is smaller than the sum.

Since N also cannot be 20 or 22, it must be less than 20. The two statements together are sufficient.

The correct answer is C.[/spoiler]

@Brent,

What about the possibilities that N can be 91, 81, 71..

For the above values Option A holds good. i.e product is less than the sum of the two digits.

In my opinion the answer should be E. I got this question while doing manhattan tests and marked E.
But as discussed in one of the above posts Manhattan says answer is C.