Which of the following are the salient features of the Patent Act 1970?1. It codifies inventions which are not patentable2. It provides for endorsement of patent with the words 'license of right'3. It provides for revocation of patents in public interest4. It has provision for validity period also for the patentsSelect the correct answer using the codes given below:

• A. 1, 2, 3 and 4
• B. 1, 2 and 4 only
• C. 1, 3 and 4 only
• D. 2 and 3 only