Final answer:
The total magnification when using a 10x ocular and a 40x high dry objective is 400x, which is obtained by multiplying the magnification of both lenses (10x40x).
Step-by-step explanation:
The total magnification of a red cell in a urine specimen viewed under a microscope with a 10x ocular and a 40x high dry objective is calculated by multiplying the magnification of the ocular lens by the magnification of the objective lens. Using the formula:
Total Magnification = Ocular lens magnification × Objective lens magnification
We get:
Total Magnification = 10x × 40x = 400x
Therefore, the correct answer is B) 400x.