Step 1: Plan:
Decide for each option whether flow resistance is the main idea.
Step 2: Evaluation:
Lubricant grading depends on resistance to flow. Blood thickness is a clinical sign linked to heart disease. Glass panes in old buildings are thicker at the base because glass flows extremely slowly. All three are viscosity effects.
Step 3: The Odd One:
Soap lifts grease by forming micelles around oil droplets. That is a surface-tension and colloid effect, not viscosity. Answer (C).
Final Answer:
Option (C) is the one that has nothing to do with viscosity.
\[ \boxed{\text{(C) Cleansing action of soap}} \]