Step 1: Understanding the Question.
The Indian Patent Act specifies certain subjects that are not patentable. Section 3 excludes methods of agriculture and horticulture, presentations of information, and topographies of integrated circuits from being patented as they are either processes of nature, mere presentations, or semiconductor designs.
Step 2: Conclusion.
Thus, all the options (a), (b), and (c) are not patentable, making (d) All of the above the correct answer.