4x A labor. 4x B human capital. C physical capital. 4x D allocation of resources.

The BEST classification for the knowledge gained by Mr. Stevens in his research would be B) human capital. Human capital refers to the knowledge, skills, and abilities that individuals possess and can use to produce economic value. In this case, Mr. Stevens' research allowed him to gain knowledge about the market demand for sports equipment in his area, which he can use to make informed decisions about what products to stock in his store.