The drilling fluid program is designed and selected according to many factors and criteria for successful drilling operations. The better the drilling fluid is designed and selected, the more efficient and effective drilling operations are possible. Answer the following Questions. i. Discuss the factors affecting the drilling fluid selection. ii. Describe the role of mud density for the successful drilling operations and also explain the potential problems during drilling operations if there are changes in mud density. iii. Describe the relationship between plastic viscosity and overall drilling performance. iv. Identify the parameters affected by the changes in Plastic viscosity which may affect the drilling performance