Answer:
The correct answer is these.
Step-by-step explanation:
Demonstrative pronouns are used to demonstrate something, or rather, point to something. In the sentence above, Maria is pointing to these flowers, and not those over there. We know exactly which flowers she is pointing to because she used the demonstrative pronoun to show us.
There is another pronoun in the sentence above, and it's the word them. However, it is a personal, rather than demonstrative pronoun.