B does not belong with the rest of them. All of them are talking about time except B
7. Me enfermaba con frecuencia, cuando 8. íbamos a la playa.
I got sick frequently when we went to the beach.
9. Tuvo por lo menos tres accidentes, 10. cuando éramos pequeños.
He had at least three accidents when we were children.
11. A menudo, los fines de semana, 12. me duele la garganta.
I often have a sore throat on weekends.
Tú lavas in preterite tense would be tú lavaste
The answer : El día de la madre