Propose a mechanism for the reaction of dimethylallyl pyrophosphate with isopentenyl pyrophosphate to form geranyl pyrophosphate.

A) Nucleophilic attack by dimethylallyl pyrophosphate on isopentenyl pyrophosphate
B) Electrophilic attack by isopentenyl pyrophosphate on dimethylallyl pyrophosphate
C) Radical coupling between dimethylallyl pyrophosphate and isopentenyl pyrophosphate
D) Acid-catalyzed condensation of dimethylallyl pyrophosphate and isopentenyl pyrophosphate