Find the sentence that is grammatically correct.

- The 1st option is incorrect as the two identical verb forms (become & disperse) have been used together.
- The sentence would have been correct if an adjective form of the verb 'disperse' was used i.e. dispersed.
- The 2nd option is incorrect as the to infinitive (to disperse) has been used after the conjunction 'that'.
- The 3rd option is incorrect as the 1st verb form (to be dispersed) is passive in nature whereas the sentence is in active voice form.
- The sentence would have been correct if a to-infinitive form of the verb 'disperse' was used i.e. to disperse.
- Thus the 4th option will be the correct choice as it follows the required structure properly.