In the xy-coordinate system, if (m, n) and (m + 2, n + k) are two points on the line with the equation x = 2y + 5, then k =	Choose the correct choice from the following options.
A) 1 / 2	B) 1	C) 2	D) 5 / 2	E) 4

Rationale: "the equation of the line can be re written as y = ( 1 / 2 ) x - 5 / 2 . slope = 1 / 2 , which means for every 1 unit increase in the y co - ordinate , x will increase by 2 units . hence k = 1 . answer : b"
Answer: B