The correct answer is: A. values of a and b
The objective of a linear cost function is to find the values of the parameters $a$ and $b$, which are the intercept and slope of the line, respectively. The values of $x$ and $y$ can be found by substituting any value of $x$ into the function.
The linear cost function is a mathematical model that describes the relationship between the cost of producing a product and the number of units produced. The function is given by the equation $y = a + bx$, where $y$ is the cost, $x$ is the number of units produced, $a$ is the intercept, and $b$ is the slope.
The intercept is the value of $y$ when $x = 0$. The slope is the rate of change of $y$ with respect to $x$. The slope tells us how much the cost changes for each unit increase in production.
The objective of a linear cost function is to find the values of $a$ and $b$. These values can be found by using the least squares method. The least squares method is a statistical method that minimizes the sum of the squared distances between the data points and the line.
Once the values of $a$ and $b$ are found, the linear cost function can be used to predict the cost of producing any number of units.