Final answer:
The correct form of the verb to fill in the blank is 'tuvo' which is option OA. 'Tuvieron' is the preterite form of the verb 'tener' (to have) in the third person singular 'él/ella/usted' ('he/she/you'). This form is used to express an action that happened in the past.
Step-by-step explanation:
The correct form of the verb to fill in the blank is 'tuvo' which is option OA. 'Tuvieron' is the preterite form of the verb 'tener' (to have) in the third person singular 'él/ella/usted' ('he/she/you'). This form is used to express an action that happened in the past, so it is appropriate for the sentence 'El diseñador tuvo un idea ayer' (The designer had an idea yesterday).
Learn more about 'El diseñador' and the correct form of the verb 'tener' in the past