El Salvador has a population density of about 620 people per square mile and neighboring Honduras a population density of about 115 people per square mile. According to the factor proportions theory of trade, one would expect El Salvador's exports to Honduras to

have a higher labor-to-land ratio than its imports from Honduras

Explanation:

The factor proportions theory (or Heckscher-Ohlin model) of trade states that countries will export the goods which they can produce using their abundant factors of production. For example, countries like Japan that have abundance of labor force and capital, but very little land, will produce and export industrial goods that require a lot of labor and capital. On the other hand, countries like Argentina which have abundant labor and land, will export agricultural products.

in this case, El Salvador compared to Honduras has abundant labor, so the products that El Salvador exports to Honduras will have a higher labor-to-land due to the abundance of labor.