Step 1: Understanding the Concept
In a rhombus, diagonals bisect each other perpendicularly. So BD passes through the midpoint of AC and is perpendicular to AC.
Step 2: Key Formula or Approach
Midpoint of AC, slope of AC, then slope of BD is the negative reciprocal.
Step 3: Detailed Explanation
Midpoint of \(A(2,-3)\) and \(C(-6,7)\): \((-2,2)\).
Slope of AC: \(\dfrac{7-(-3)}{-6-2}=-\dfrac{5}{4}\), so the slope of BD is \(\dfrac45\).
Line through \((-2,2)\): \(y-2=\dfrac45(x+2)\), so \(5y-10=4x+8\), which gives
\[ 4x-5y+18=0 \]
Final Answer:
The diagonal BD is \(4x-5y+18=0\), option (C).
\[ \boxed{4x-5y+18=0\ \text{(C)}} \]