Answer:
Defining relative clause
Explanation:
Defining relative clause are sentences used to display essential information from previously used sentences or terms, that is, these clauses are added in a text to increase the understanding of something that was previously presented. These clauses are usually separated from the rest of the text by commas, parentheses and even dashes.
In relation to the sentence above, we can see that the sentence "that demonstrated the effect of garlic on the cancer cells" is referring to and adding explanatory information to the term "The new research" written earlier. For this reason, we can consider it a defining relative clause.
