Find the Marginal Revenue for Producing X Units $R = 50 x - 0.5 x ^ { 2 }$

Multiple Choice

Find the marginal revenue for producing x units. (The revenue is measured in dollars.) $R = 50 x - 0.5 x ^ { 2 }$

A) $50 - x \text { dollars }$
B) $50 + x \text { dollars }$
C) $50 \text { dollars }$
D) $50 - 0.5 x \text { dollars }$
E) $50 + 0.5 x \text { dollars }$