On the basis of stereochemistry, explain why the following reaction does not occur via the S_N2 mechanism.

• A. A more stable z-alkene is formed.
• B. The nucleophile is added to less sterically hindered carbon.
• C. The stereochemistry of the alkene is conserved in the product.
• D. There is an inversion of stereochemistry in the product.

Answer: (C)