Step 1: Concept
The perpendicular distance $d$ between two parallel lines $Ax + By + C_1 = 0$ and $Ax + By + C_2 = 0$ is given by:
\[ d = \frac{|C_1 - C_2|}{\sqrt{A^2 + B^2}} \]
Step 2: Meaning
For the given parallel lines, we have $A = 5$, $B = 12$, $C_1 = -3$, and $C_2 = 10$.
Step 3: Analysis
Substituting the values into the formula:
\[ d = \frac{|-3 - 10|}{\sqrt{5^2 + 12^2}} \]
\[ d = \frac{|-13|}{\sqrt{25 + 144}} = \frac{13}{\sqrt{169}} = \frac{13}{13} = 1 \]
Step 4: Conclusion
The distance between the parallel lines is $1$ unit.
Final Answer: (A)