Given below are two statements :

Statement I :
Modal verbs have only one form. They have no -ing or -ed forms and do not add -s to the $$3^{rd}$$ person singular form.

Statement II :
Modal verbs are followed by past participle form of the other verbs.

In the light of the above statements, choose the correct answer from the options given below:

Modal verbs are auxiliary verbs that express modality, indicating possibility, ability, permission, necessity, or obligation. For example: "She can swim."

Statement I: This is correct; modal verbs have only one form (for example, can, may, should and so on); they do not have -ing or -ed forms. 

Statement II: This is incorrect; modal verbs are not followed by the past participle directly, but by the base form of the verb. 

Therefore, Option C is the correct answer.