According to the Fundamental Theorem of Algebra, a polynomial of degree \( n \) has exactly \( n \) roots, counting multiplicities, in the complex number system. In your case, the polynomial has a term \( 8x^5 \), meaning it is of degree 5.
From this, we can conclude that:
- The polynomial has **exactly 5 roots** (which could be real or complex).
Now, let's analyze each of the provided statements:
1. **The equation has an odd number of real roots.** - This statement is not necessarily true; the polynomial could have 5 real roots, 3 real roots and 2 complex roots, 1 real root and 4 complex roots, or 5 complex roots (where complex roots come in conjugate pairs).
2. **The equation has at least 5 roots.** - This statement is true because a degree 5 polynomial has exactly 5 roots, so "at least 5" qualifies.
3. **The equation has more than 5 roots.** - This statement is false since a degree 5 polynomial can only have 5 roots.
4. **All the roots of the equation are real.** - This statement is also not necessarily true; the roots can be a combination of real and complex roots.
Therefore, the correct statement that must be true is:
**The equation has at least 5 roots.**