Step 1: National Political Parties in India 
  
As per the Election Commission of India, a national party is a party which secures at least 6% of the total votes in any four or more states and has at least 4 seats in the Lok Sabha. 
  
Step 2: Current National Parties 
  
Currently, India has five national political parties, which are: 
  
1. Bharatiya Janata Party (BJP) 
  
2. Indian National Congress (INC) 
  
3. Communist Party of India (CPI) 
  
4. Communist Party of India (Marxist) - CPI(M) 
  
5. Nationalist Congress Party (NCP) 
  
Step 3: Conclusion 
  
Thus, the correct answer is option (B) Five. 
Find the unknown frequency if 24 is the median of the following frequency distribution:
\[\begin{array}{|c|c|c|c|c|c|} \hline \text{Class-interval} & 0-10 & 10-20 & 20-30 & 30-40 & 40-50 \\ \hline \text{Frequency} & 5 & 25 & 25 & \text{$p$} & 7 \\ \hline \end{array}\]