How long was the dmz that separated north from south vietnam

People keep spending additional units of a particular resource on a want until their marginal benefit is  decreasing withgreater thanless thannot affected by  their marginal cost.

Which of the following statements best characterizes changes to agriculture in the united states since 1900? a. increased mechanization has reduced the need for labor.b. increased mechanization has increased the need for water, thereby increasing the need for labor.increased mechanization has increased the use of land, thereby increasing the need for labor.d. increased mechanization has increased food production, thereby increasing the need for labor. select the best answer from the choices provided.

Which are evidence of the seafloor spreading? a. molten material b. magnetic stripes c. continental material d. drilled core samples e. ocean water samples