In general, alkenes are more reactive to electrophiles than their corresponding alkynes. However, this reactivity difference is much greater and more evident in the addition of HBr as compared to the addition of Br₂. Explain why this is the case. 

• A. The π electrons of alkenes are more tightly held and the carbocation formed from the alkene protonation step of HBr addition is less stable. These factors increase the reaction rate of alkenes more compared to the factor of more ring strain present in the rate-determining step of Br₂ addition.
• B. The π electrons of alkenes are more tightly held and the carbocation formed from the alkene protonation step of HBr addition is less stable. These factors increase the reaction rate of alkenes more compared to the factor of less ring strain present in the rate-determining step of Br₂ addition.
• C. The π electrons of alkenes are more tightly held and the carbocation formed from the alkene protonation step of HBr addition is more stable. These factors increase the reaction rate of alkenes more compared to the factor of less ring strain present in the rate-determining step of Br₂ addition.
• D. The π electrons of alkenes are more loosely held and the carbocation formed from the alkene protonation step of HBr addition is more stable. These factors increase the reaction rate of alkenes more compared to the factor of less ring strain present in the rate-determining step of Br₂ addition.

Answer: (D)