The area under a straight line is an estimate of the integral of f(x) between the limits a and b and the result of this integration is called the trapezoidal rule. The formula used in area calculation by this rule is

• A. \(I = \left( {a - b} \right)\frac{{f\left( a \right) + f\left( b \right)}}{4}\)
• B. \(I = \left( {b - a} \right)\frac{{f\left( b \right) - f\left( a \right)}}{2}\)
• C. \(I = \left( {b - a} \right)\frac{{f\left( a \right) + f\left( b \right)}}{2}\)
• D. \(I = \left( {b - a} \right)\frac{{f\left( a \right) + f\left( b \right)}}{3}\)