Pick up the correct statement from the following :

• Rate of digestion of slugde is more at higher temperature
• Thermophilic organisms digest the sludge if the temperature ranges from 40° to 60°C
• Mesophilic organisms digest the sludge if the temperature is between 25° and 40°C
• 90% of digestion takes place in 30 days at 29°C, the optimum mesophilic temperature
• All the above.