The question asks which section of the Patent Act, 1970, specifies the subject matters that are not considered inventions under the Act. Let us examine each option:

1. Section 7: This section deals with the form and manner of making applications for patents. It specifies the procedure for the submission of patent applications. It is not related to subject matters that are not inventions.
2. Section 3: This section is indeed the relevant part of the Patent Act, 1970, which lists the subject matters that are not considered inventions. It details exclusions from being classified as inventions, including discoveries, scientific theories, mathematical methods, literary works, and more.
3. Section 10: This section concerns the contents of specifications of patents, including what these must contain and how they should be filed. It does not address non-inventions.
4. Section 11: This section pertains to the publication of applications and not the exclusion of certain subjects from being considered inventions.

Therefore, the correct answer is Section 3. This section specifically delineates what is excluded as an invention under the Indian Patent Act.

In conclusion, Section 3 of the Patent Act, 1970, provides clarity on what cannot be patented in India by listing any exclusions or what is deemed non-inventive. This understanding is crucial for anyone preparing for exams in Law or related subjects.