Which projection maps the world onto a cylinder with parallels the same length as the equator, commonly used for marine charts?

• A. Mercator Projection (Cylinder)
• B. Conic Projection (Cone)
• C. Gnomonic Projection (Single Point)
• D. Topographic Map

Answer: (A)

A cylinder-wrapped projection keeps the globe on a cylinder tangent at the equator, so every parallel of latitude becomes a straight line across the map and all those parallels have the same length on the map as the equator does. This is the Mercator projection. It preserves angles locally, which means compass directions stay reliable for small distances, and lines of constant bearing (rhumb lines) plot as straight lines, a major advantage for marine navigation. The other options don’t fit: a conic projection uses a cone, not a cylinder; a gnomonic projection maps from a single point onto a plane and isn’t the standard for navigational charts; a topographic map is a type of map, not a specific projection.