Find the sum: (x8 + 3x6 - 4x4 + 10x) + (2x7 - 4x5 - x3 + 10).

A. 3x7 - 7x5 - x2 + 20

B. x8 + 2x7 + 3x6 - 4x5 - 4x4 + x2 + 9x + 10

C. 2x7 + 4x6 + 2x5 - 2x4 - 5x3 - x2 + 17x + 17

D. x8 + 2x7 + 3x6 - 4x5 - 4x4 - x3 + 10x + 10

We are being tasked to solve the summation of the two expressions (x8 + 3x6 - 4x4 + 10x) + (2x7 - 4x5 - x3 + 10). To answer this, we need and we can only combine terms in the same degree or power. Upon evaluation of the two expressions, all terms have different power and hence we have the combination of the two as the result of the summation such as:

x ⁸ + 3x⁶ - 4x⁴ + 10x + 2x⁷ - 4x⁵ - x³ + 10 = 0

Arrange the power in descending order such as:

x⁸ + 2x⁷ + 3x⁶ - 4x⁵ - 4x⁴ - x³ + 10x + 10 = 0

The answer is the letter "D".