Ice Cream advertising questions seemed to have two response categories: 'Yes' and 'Don't know'. Surely 'No' is a response?
Even if your client doesn't need to differentiate between 'Don't know' and 'No', you would want to encourage people to answer accurately for the sake of other survey instruments when there is an important difference between negative response categories.
I agree with you there and actually did answer no rather than yes or dont know lol