Arithmetic growth is a type of growth where a quantity increases or decreases by a fixed amount over a fixed interval of time. It can be represented mathematically using the formula Lt = L0 + rt, where Lt is the value of the quantity at time t, L0 is the initial value of the quantity, r is the rate of change, and t is the time interval.

Explanation of the formula:
- Lt represents the value of the quantity at time t. This is the value that we want to find.
- L0 represents the initial value of the quantity. This is the starting point of the growth.
- r represents the rate of change. It determines how much the quantity changes over the time interval.
- t represents the time interval. It is the amount of time that has passed since the initial value.

In arithmetic growth, the rate of change is constant. This means that the quantity increases or decreases by the same amount for each unit of time. The formula Lt = L0 + rt captures this concept by adding the rate of change multiplied by the time interval to the initial value.

For example, let's say we have an initial quantity of 100 and a rate of change of 5. If we want to find the value of the quantity after 3 time intervals, we can use the formula Lt = 100 + 5 * 3 = 115. This means that the quantity has increased to 115 after 3 time intervals.

In option C, Lt = L0 + rt, the formula correctly represents arithmetic growth. The other options do not accurately capture the concept of arithmetic growth or contain incorrect mathematical operations.