The correct answer is:

a. those

Explanation:
In English, "those" is used to refer to people or things that are at some distance from the speaker, both physically and contextually. In this sentence, "those" is appropriate because it refers to people who are over there near the bank, indicating they are not close to the speaker.

- "This" is used for singular nouns that are close to the speaker.
- "That" is used for singular nouns that are at a distance from the speaker.
- "Those" is the plural form of "that" and is used for plural nouns that are at a distance from the speaker.

So, the correct sentence is: "Do you know those people over there near the bank?"