Let the breadth of the rectangle be \(x\) meters. Then the length will be \(x + 1\) meters.
The area of a rectangle is given by:
\[
\text{Area} = \text{Length} \times \text{Breadth}
\]
Given that the area is 30 m², we have:
\[
(x + 1) \times x = 30
\]
Simplifying the equation:
\[
x^2 + x = 30
\]
Rearrange to get the quadratic equation:
\[
x^2 + x - 30 = 0
\]
Thus, the quadratic equation to find the length and breadth is \( x^2 + x - 30 = 0 \). The correct answer is (C).