Which function g represents the exponential function f(x) = 5x after a vertical stretch by a factor of 2 and a reflection across the x-axis? A. g(x) = (2 ⋅ 5)−x B. g(x) = −(2 ⋅ 5)x C. g(x) = 2 ⋅ (5)−x D. g(x) = −2 ⋅ (5)x