Which of the following is true?

Options

A. In retina opsin protein combines with 11-cisretinol to form rhodopsin
B. Rods are primarily responsible for vision in dim S light
C. Cones are responsible for vision in bright light and for colour detection
D. All of the above

Answer

To determine which of the following statements is true, we will analyze each statement step by step.

### Step 1: Evaluate the First Statement
**Statement**: In the retina, opsin proteins combine with 11-cis-retinol to form rhodopsin.

**Analysis**: This statement is true. In the retina, the opsin protein indeed combines with 11-cis-retinol (a form of vitamin A) to form rhodopsin, which is crucial for the phototransduction process in rod cells.

### Step 2: Evaluate the Second Statement
**Statement**: Rods are primarily responsible for vision in dim light.

**Analysis**: This statement is also true. Rod cells are specialized photoreceptors in the retina that are highly sensitive to light and are responsible for scotopic (dim light) vision.

### Step 3: Evaluate the Third Statement
**Statement**: Cones are responsible for vision in bright light or for color detection.

**Analysis**: This statement is true as well. Cone cells function best in bright light conditions and are responsible for color vision and high spatial acuity.

### Step 4: Evaluate the Fourth Statement
**Statement**: All of the above.

**Analysis**: Since all the previous statements (1, 2, and 3) are true, this statement is also true.

### Conclusion
Based on the analysis of all statements, the correct answer is **Option 4: All of the above**.

---