Carcass wrote:

Sorry, sometimes the forum does not show properly the formatting (or maybe I am wrong).

It is NOT \(2n + 1\) but it is (if you notice very carefully) that 2 (in the first quantity) is \(2^{n+1}\)

Ok, yes the forum wasn't showing it right.

Thanks

I edit my answer then. The exponent in quantity A can be rewritten as \(2^{n+1} = 2n+2\). Thus, the exponent is always even and -1 to an even exponent becomes 1, so the answer would be C, not D. Sorry for bothering you but may you provide the OE?