## Core Concept
The question tests knowledge of medications that can cause pigment deposition on the cornea, a condition known as corneal pigmentation or deposition. This can occur due to the long-term use of certain drugs.

## Why the Correct Answer is Right
Corneal pigmentation is a known side effect of several medications. Among the options provided:
- **Chloroquine**, an antimalarial drug, is well-documented to cause corneal deposits, particularly with long-term use. These deposits can be reversible upon cessation of the drug.
- **Amiodarone**, an antiarrhythmic medication, is also known to cause corneal deposits. These are usually harmless but can be a significant side effect.
- **Digoxin** and **Ranitidine** are not commonly associated with corneal pigmentation.

## Why Each Wrong Option is Incorrect
- **Option B: Digoxin** - Digoxin is primarily used in the treatment of heart failure and atrial fibrillation. It is not commonly associated with corneal deposits.
- **Option C: Ranitidine** - Ranitidine is an H2 receptor antagonist used to reduce stomach acid. It is not typically associated with corneal pigmentation.
- **Option A: Chloroquine** and **Option D: Amiodarone** are both correct associations, but since the prompt requires identification of incorrect options and given that **D. Amiodarone** along with **a) Chloroquine** are correct, **B** and **C** are incorrect.

## Clinical Pearl / High-Yield Fact
A key point to remember is that chloroquine and hydroxychloroquine can cause corneal deposits, and regular ophthalmological monitoring is recommended for patients on long-term therapy. Amiodarone-induced corneal deposits are usually harmless but indicate the need for monitoring.

## Correct Answer: D.