Step 1: Understanding the Legal Context of Surrogacy in India. 
  
Surrogacy laws in India have undergone significant changes in recent years. The Surrogacy (Regulation) Bill, 2019, prohibits commercial surrogacy, but it allows altruistic surrogacy. Altruistic surrogacy refers to when a woman carries a child for another person without monetary compensation, except for medical and other necessary expenses.
Step 2: Analyzing the Options. 
  
- 1. Commercial Surrogacy: This is illegal in India under the Surrogacy (Regulation) Bill, 2019. Commercial surrogacy involves monetary compensation beyond medical expenses, which is prohibited.  
- 2. Altruistic Surrogacy: This is correct. Altruistic surrogacy is allowed in India, where the surrogate mother is not paid except for medical expenses.  
- 3. Corporate Surrogacy: This is not recognized as a legal form of surrogacy in India.  
- 4. Commodified Surrogacy: This refers to treating surrogacy as a business transaction, which is illegal in India.
Step 3: Conclusion.  
The correct answer is 2. Altruistic Surrogacy.
  
 
Final Answer:  
\[  
\boxed{\text{The correct answer is 2. Altruistic Surrogacy.}}  
\]