Let's solve each of the options and see which one simplifies to $4x - 3$.

Option 1:

$-2x + 6x - 8 - 5$

Simplify: $-2x + 6x = 4x$ $-8 - 5 = -13$ Thus, the expression simplifies to: $4x - 13$ This is not equal to $4x - 3$.

Option 2:

$15 + 7x - 3x - 12$

Simplify: $7x - 3x = 4x$ $15 - 12 = 3$ Thus, the expression simplifies to: $4x + 3$ This is not equal to $4x - 3$.

Option 3:

$9x^2 + 4 - 5x^2 - 7$

Simplify: $9x^2 - 5x^2 = 4x^2$ $4 - 7 = -3$ Thus, the expression simplifies to: $4x^2 - 3$ This is not equal to $4x - 3$, since the degree of the polynomial is different.

Option 4:

$5x - 2 - x - 1$

Simplify: $5x - x = 4x$ $-2 - 1 = -3$ Thus, the expression simplifies to: $4x - 3$ This matches $4x - 3$.

Conclusion:

The correct answer is Option 4: $5x - 2 - x - 1$.

Do you need more details or have any questions about this solution?

Here are five related questions:

1. How do you simplify expressions with variables?
2. What is the degree of a polynomial and how does it affect simplification?
3. Can you explain how like terms are combined in algebra?
4. Why does Option 3 not simplify to $4x - 3$?
5. How do constants affect the result when simplifying an expression?

Tip: Always group like terms together (terms with the same variable or constant) before simplifying.