Which of the following 2,3-dibromobicyclo[2.2.1]heptane would undergo an elimination reaction much faster? Explain these large rate differences.

• A. The cis isomer has H and Br atoms in an anti-periplanar configuration, while they are not anti-periplanar in the trans isomer.
• B. The trans isomer has H and Br in a syn-coplanar configuration, while they are not syn-coplanar in the cis isomer.
• C. The trans isomer has H and Br in an anti-coplanar configuration, while they are not anti-coplanar in the cis isomer.
• D. The cis isomer has H and Br in a anti-coplanar configuration, while they are not coplanar in the trans isomer.

Answer: (A)