A line x \equal{} k intersects the graph of y \equal{} \log_5{x} and the graph of y \equal{} \log_5{(x \plus{} 4)}. The distance between the points of intersection is 0.5. Given that k \equal{} a \plus{} \sqrt{b}, where a and b are integers, what is a \plus{} b?
<spanclass=′latex−bold′>(A)</span>6<spanclass=′latex−bold′>(B)</span>7<spanclass=′latex−bold′>(C)</span>8<spanclass=′latex−bold′>(D)</span>9<spanclass=′latex−bold′>(E)</span>10