Step 1: Understanding ecosystem services.
Ecosystem services are broadly classified into provisioning, regulating, cultural, and supporting services. Wildlife regulatory services fall under regulating services, which help maintain ecological balance.
Step 2: Role of regulatory services.
Regulating services include climate regulation, disease control, pollination control, and population regulation. Wildlife contributes indirectly to ecosystem stability through these functions.
Step 3: Percentage distribution concept.
In standard ecological classification, regulating services contribute a relatively small fraction compared to provisioning services, which dominate human usage patterns.
Step 4: Data-based identification.
As per ecological service distribution models, wildlife regulatory services are approximately 6% of total ecosystem services.
Step 5: Comparative reasoning.
Higher percentages like 12%, 18%, and 24% do not match standard ecological breakdowns of regulatory contributions.
Step 6: Final conclusion.
Thus, the correct answer is 6%.