Determining the product which is not possible in the reaction

This is an objective type question I encountered in a objective test.


[![enter image description here](https://i.stack.imgur.com/Qk3XZ.png)](https://i.stack.imgur.com/Qk3XZ.png)


NBS (*N*-bromosuccinimide) is used for the allylic substitution of $\ce{Br}$ in a reaction. In this reaction, since the allylic carbon is the carbon adjacent to the carbon having double bonds, I thought that options B), C) and D) all can be the products but not A). However, the answer key gives the answer as D) and I can't understand why it should be?




@Pete
B1 is same as D1


But, D1 & D2 are not same.


@Aniline
I see some problem in the options while it was framed/typed/published


I have shown the 6 possible stereoisomers, which have have labelled independently as A, B, C, D, E & F


For the sake of clarity have generated their names with some software [not from my own] to be assured that these are actually different or same compounds.


Showing the mechanism, how there is a possibility of getting SIX by a free radical mechanism:


[![enter image description here](https://i.stack.imgur.com/nMtQX.jpg)](https://i.stack.imgur.com/nMtQX.jpg)


This one a redraw of the options A, B, C & D with their names:
[![enter image description here](https://i.stack.imgur.com/Rzz7x.jpg)](https://i.stack.imgur.com/Rzz7x.jpg)


The relationship of D1 & D2 as per question doesn't work to the the same:[![enter image description here](https://i.stack.imgur.com/cWKY9.jpg)](https://i.stack.imgur.com/cWKY9.jpg)


In my opinion, there are six stereoisomers possible, but the correct option does not exist, in the question[options given, in fact].


Hope it throws some more light on your query.


 3

~~**D** is a product, but only one product. Not two products. Those two are the same molecule flipped on a mirror plane. Were the molecule chiral (having an non-superimposable asymmetric center), then it could be two products. Not as it sits now.~~ 


Notice D1 is the same as B1. ~~D2 is also B1, but flipped. Six products.~~


**D2** is an enantiomer of **D1**, but not identical to it. I cannot puzzle out how D is supposed to be the correct answer. 


 2

The second product in Option **D)** is not a product of this reaction.


You cannot rotate the substrate molecule in such a way that the Me substituent ends up in the portraied position.


 0