To accurately answer this question, I would need the specific details or information provided in question 1a, which seems to pertain to the length and width of the shelter. Since I don't have that information, I can't determine the width based on your options.
However, if you know the length and the relationship between the length and width, you can use that to find the width. For example, if the length is greater than the width and follows a specific ratio, you would apply that.
If you can provide the dimensions or any relevant information from question 1a, I would be happy to assist you further!