Simplify the expression: 13a + 2b - 3c - 7a - 4b + 8b. Assume the last term is 8c.

To simplify the expression, we need to combine like terms.

The expression given is:

$$13a + 2b - 3c - 7a - 4b + 8b$$

Upon careful examination of the question and the provided multiple-choice options, it appears there might be a typographical error in the last term. If we strictly interpret the term as $8b$, the simplified expression would be $6a + 6b - 3c$, which is not among the given options. However, if we assume that the term $8b$ was intended to be $8c$ (a common visual ambiguity in handwritten questions), then one of the options matches perfectly. We will proceed with the assumption that the last term is $8c$.

Assuming the expression is:

$$13a + 2b - 3c - 7a - 4b + 8c$$

Step 1: Group the terms with 'a'.

$$(13a - 7a)$$

Step 2: Group the terms with 'b'.

$$(2b - 4b)$$

Step 3: Group the terms with 'c'.

$$(-3c + 8c)$$

Step 4: Combine the coefficients for each group.
For 'a' terms:

$$13a - 7a = (13 - 7)a = 6a$$

For 'b' terms:

$$2b - 4b = (2 - 4)b = -2b$$

For 'c' terms:

$$$$