Final answer:
The correct form for the sentence is 'resemble'. The verb 'resemble' is used to indicate a physical similarity.
Step-by-step explanation:
The correct form for the sentence is resemble.
In this sentence, the verb 'resemble' is used to indicate that the person being referred to (you) has a physical similarity to their father when they frown. The verb 'resemble' is in the present tense because it is describing a general and ongoing characteristic.
For example, you could say: 'You resemble your father when you frown like that.' This sentence implies that there is a resemblance between you and your father in that particular facial expression.