The surface area of the crate is the summation of all the areas of its six faces. The area of the two of its faces is the product of 50 cm and 70 cm which is 3500 cm^2. The other will have an area of 2000 cm^2. The last two will have the area of 2800 cm^2. Thus, the unit of measurement used to figure out the surface area is the cm^2. The answer is letter A. cm2
