Eleven men and women in cotton shirts and denim pants walk uphill along a shaded forest trail .
It is certain that the 11 couples are on their way to the park for a picnic
It is impossible that the 11 couples are on their way to the park for a picnic
It is certain that the 11 couples are on their way to the park for a picnic
The 11 couples are on their way to the park for a picnic