Step 1: Understanding the Concept
A general point on the line is \(P(7-2t,\,7+2t,\,6+3t)\). Let \(A=(3,2,1)\).
Step 2: Join A and P
\(\overrightarrow{AP}=(4-2t,\;5+2t,\;5+3t)\).
Step 3: Perpendicular condition
The direction ratios of the line are \((-2,2,3)\).
\(-2(4-2t)+2(5+2t)+3(5+3t)=17+17t=0\Rightarrow t=-1\).
Step 4: Distance
For \(t=-1\): \(\overrightarrow{AP}=(6,3,2)\), so \(k=\sqrt{36+9+4}=\sqrt{49}=7\).
Final Answer:
The length of the perpendicular is 7 units.
\[ \boxed{\text{(C) }7} \]