Which object will have particles with the highest average kinetic energy?

To determine which object has particles with the highest average kinetic energy, we need to consider the temperature of each substance, as the average kinetic energy of particles in a substance is directly related to its temperature in Kelvin.

1. **Water at 40°C**: 40 + 273.15 = 313.15 K
2. **Iceberg at 0°C**: 0 + 273.15 = 273.15 K
3. **Drop of water at 90°C**: 90 + 273.15 = 363.15 K
4. **Water at 37°C**: 37 + 273.15 = 310.15 K

Comparing the temperatures in Kelvin:
- Water at 40°C: 313.15 K
- Iceberg at 0°C: 273.15 K
- Drop of water at 90°C: 363.15 K
- Water at 37°C: 310.15 K

The drop of water at 90°C has the highest temperature (363.15 K), which means it has the highest average kinetic energy of its particles.

Therefore, the answer is **a drop of water at 90°C**.