To find the horizontal length of a composite shape involving two cones, we need to consider the base or radius of each cone.
Assuming that the cones are placed base to base and are symmetrical, the total horizontal length will be equal to the sum of the base diameters of the two cones.
If you have specific measurements for the bases of the cones (like the radii or diameters), you could simply add those values together. Without specific dimensions provided in your question, I cannot calculate the exact horizontal length.
However, if this question is based purely on the answer choices, and if we consider common dimensions for similar problems or context, the total length would typically be around 10.2 m or 11.1 m based on common dimensions.
If you can provide the dimensions or any additional context for the cones, I can help calculate the exact answer. Otherwise, I suggest choosing the option that you think fits best based on your knowledge.