Step 1: Understanding the criteria of effective planning. 
  
Effective planning requires a combination of several key criteria: flexibility, practicability, and futurity. A good plan must be adaptable (flexibility), feasible (practicability), and consider long-term outcomes (futurity). All of these qualities are essential for successful planning. 
Step 2: Analyzing the options. 
  
(A) Flexibility: Correct. Plans need to be flexible to adapt to changing conditions. 
  
(B) Practicability: Correct. The plan should be realistic and achievable. 
  
(C) Futurity: Correct. Planning should take into account the future consequences and needs. 
  
(D) All of these: Correct. All these criteria are important in effective planning. 
Step 3: Conclusion. 
  
The correct answer is (D) All of these, as all these factors contribute to effective planning.