Which of the following options is CORRECT ?

Options

A. Two rational numbers with different denominators can never be equal.
B. The rational number `-2/3` lies on the right of 0 on the number line.
C. Difference of two rational numbers is always a rational number.
D. The standard form of `(-18)/(-24)` is `-3/4`.

Answer

To solve the question, we need to evaluate each of the given options and determine which one is correct.

### Step-by-Step Solution:

1. **Evaluate Option 1**: "Two rational numbers with different denominators can never be equal."
- **Explanation**: This statement is false. Rational numbers can be equal even if they have different denominators. For example, \( \frac{2}{6} \) and \( \frac{3}{9} \) are equal because when simplified, both equal \( \frac{1}{3} \).

2. **Evaluate Option 2**: "The rational number -\(\frac{2}{3}\) lies on the right side of 0 on the number line."
- **Explanation**: This statement is also false. On a number line, negative numbers lie to the left of 0. Therefore, -\(\frac{2}{3}\) is located on the left side of 0.

3. **Evaluate Option 3**: "The difference of two rational numbers is always a rational number."
- **Explanation**: This statement is true. The difference of two rational numbers (for example, \( \frac{a}{b} - \frac{c}{d} \)) can be expressed as \( \frac{ad - bc}{bd} \), which is also a rational number.

4. **Evaluate Option 4**: "The standard form of the difference of two rational numbers is always a rational number."
- **Explanation**: This statement is misleading. While the difference of two rational numbers is rational, the claim about the standard form needs clarification. The standard form of a rational number is simply its simplest form, which can still be rational. However, the statement is vague and can be considered false in this context.

### Conclusion:
After evaluating all the options, we find that only Option 3 is correct: "The difference of two rational numbers is always a rational number."