1. Identify the substrate and reagent behavior

   The reaction involves a benzylic halide of the type $C_6H_5CH(X)CH_2C_6H_5$ reacting with tert-butoxide $t ext{-}BuO^-$.

   Here, $t ext{-}BuO^-$ is:

   • a strong base
   • a bulky nucleophile/base

   Therefore, it strongly favors elimination ($E2$) over substitution.

2. Check possible pathways

   Possible products shown are:

   • Elimination product: $C_6H_5CH=CHC_6H_5$
   • Substitution products: $C_6H_5CH(Ot ext{-}Bu)CH_2C_6H_5$ with chiral possibilities: $(+), (-), (\pm)$

3. Why elimination is favored

   In benzylic halides, substitution can occur, but with $t ext{-}BuO^-$ the steric hindrance makes backside attack difficult.

   The substrate has a suitable $\beta$-hydrogen on the adjacent $CH_2$ group, so an $E2$ reaction can occur easily: $C_6H_5CH(X)CH_2C_6H_5 \xrightarrow[t ext{-}BuO^-]{} C_6H_5CH=CHC_6H_5$

4. Stability of the alkene formed

   The alkene obtained is $C_6H_5CH=CHC_6H_5$ which is stilbene, a highly stabilized alkene due to conjugation with two phenyl rings.

   This makes elimination especially favorable.

5. Why substitution products are not major

   If substitution occurred, it would give $C_6H_5CH(Ot ext{-}Bu)CH_2C_6H_5$ and depending on mechanism could give enantiomers.

   However, because the reagent is bulky and strongly basic, substitution is minor compared with elimination.

6. Conclusion

   Therefore, the major product is: $C_6H_5CH=CHC_6H_5$

   So the correct option is A.

Comparison with stored correct answer

Stored correct answer: A

My derived answer: A

They agree.