Which of the following is a characteristic of a mineral? 

A)  A mineral is organic. 
B)  A mineral has a regular crystalline structure. 
C)  A mineral can be liquid. 
D)  A mineral can only be made by humans.

A mineral is defined as a naturally occurring inorganic substance with a regular crystalline structure. Option A is incorrect because minerals cannot be organic. Option C is incorrect because minerals can exist in solid, liquid, and gaseous states, but only the solid form is considered a mineral. Option D is incorrect because minerals occur naturally and are not created by humans.