Step 1: Understanding the role of titanium dioxide in capsules.
Titanium dioxide is commonly added to gelatin capsules to make them opaque. This is done to protect the contents of the capsule from light and to make the capsule more visually appealing.
Step 2: Analyzing the options.
(A) Tonicity contributor: This is incorrect, as titanium dioxide does not influence the tonicity of the capsule.
(B) Viscosity inducer: This is not correct; titanium dioxide does not affect the viscosity of the capsule material.
(C) Opacifier: Correct — Titanium dioxide is an opacifier, meaning it makes the capsule opaque by blocking light.
(D) Preservative: Titanium dioxide is not a preservative; it is not used to preserve the drug.
Step 3: Conclusion.
The correct answer is (C) Opacifier because titanium dioxide is used to make capsules opaque.