What are the demonstrative pronouns used in the examples?

The examples illustrate the usage of 'this,' 'that,' 'these,' and 'those' to refer to objects. Specifically: 1. 'This is my pen.' ('This' refers to a singular object close to the speaker.) 2. 'That is my ruler.' ('That' refers to a singular object farther away from the speaker.) 3. 'These are my pens.' ('These' refers to plural objects close to the speaker.) 4. 'Those are my rulers.' ('Those' refers to plural objects farther away from the speaker.)