The passage states that "Grandad would drive us in his old van."
Option 4 says "Grandma would drive the narrator in her old van."
This is incorrect — it was Grandad, not Grandma, who drove the narrator in his old van.
The other three options are all accurately reflected in the passage:
Option 1: "Several hours of picking berries ensured."
Option 2: "Juice bled slowly onto the ground."
Option 3: "It was usually late August when the blackberries had fully ripened."
Therefore, Option 4 is the incorrect statement.