The correct answer is "1 only" which refers to statement I. This is because historical periods, including the Stone Age era in India, are often identified by the type and technology of tools used during that time. This includes stone tools which were prevalent during the Stone Age.

Option 2 is incorrect as there were indeed regional variations in the type and technology of tools in different periods even during the Stone Age. Different regions had different resources, affecting the types of tools they could create.

Option 3 is also incorrect. The assertion that Stone Age cultures evolved uniformly all over the subcontinent is not true. Cultural evolution, including tool use, is impacted by a variety of factors such as geography, climate, and interaction with other cultures - all of which can vary widely across different regions.

Option 4, which suggests that all three statements are correct, is also incorrect because, as explained above, statements II and III are not accurate reflections of the historical record.