Exponential growth or geometric growth is represented by :-

Options

A. `N_(t+1) = N_(f) + [(B+P) - (D+E)]`
B. `(dN)/(dt) = (b-d) xx N`
C. `(dN)/(dt) = rN ((K-N)/(K))`
D. `(dN)/(dt) = KN`

Answer

To solve the question regarding the representation of exponential growth or geometric growth, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Exponential Growth**:
- Exponential growth, also known as geometric growth, occurs when the number of individuals in a population increases at a constant rate over time, under ideal conditions.

2. **Identify the Key Equation**:
- The mathematical representation of exponential growth is given by the equation:
\[ \frac{dn}{dt} = rn \]
- Here, \( \frac{dn}{dt} \) represents the change in population size over time, \( r \) is the maximum per capita growth rate, and \( n \) is the number of individuals in the population.

3. **Analyze the Options**:
- The question provides several options to determine which one correctly represents exponential growth.
- The first option is \( n t - 1 \), which does not include the necessary components of the exponential growth equation, making it incorrect.
- The second option is \( \frac{dn}{dt} = b - d \), where \( b \) is the birth rate and \( d \) is the death rate. This equation does not represent exponential growth directly but rather the net change in population, making it also incorrect.
- The third option, \( \frac{dn}{dt} = r n (k - n)/k \), represents logistic growth, which occurs when resources are limited, thus making it incorrect for exponential growth.
- The fourth option, \( \frac{dn}{dt} = kn \), is incorrect as it introduces the variable \( k \), which is not part of the exponential growth equation.

4. **Conclusion**:
- The only correct representation of exponential growth is the equation \( \frac{dn}{dt} = rn \). Therefore, the correct answer to the question is the second option.

### Final Answer:
The exponential growth or geometric growth is represented by:
\[ \frac{dn}{dt} = rn \]