The change in population size at a given time interval t, is given by the expression
Nt = No+ B + I - D - E
I, B and D stand respectively for

Options

A. Rate of immigration, mortality rate, natality rate
B. Rate of immigration, natality rate, rate of emigration
C. Mortality rate, natality rate, rate of immigration
D. Rate of immigration, natality rate, mortality rate

Answer

To solve the question regarding the expression for the change in population size at a given time interval \( t \), we need to identify what \( I \), \( B \), and \( D \) stand for in the equation:

\[ N_t = N_0 + B + I - D - E \]

### Step-by-Step Solution:

1. **Understanding the Variables**:
- \( N_t \): This represents the population size at time \( t \).
- \( N_0 \): This is the initial population size.
- \( B \): This stands for the natality rate, which is the total number of births in the population during the time interval.
- \( I \): This represents the rate of immigration, which is the total number of individuals that move into the population.
- \( D \): This is the mortality rate, which is the total number of deaths in the population during the time interval.
- \( E \): This is the emigration rate, which is the total number of individuals that leave the population.

2. **Identifying \( I \), \( B \), and \( D \)**:
- From the equation, we can identify:
- \( B \) is the **natality rate**.
- \( I \) is the **rate of immigration**.
- \( D \) is the **mortality rate**.

3. **Conclusion**:
- Therefore, the meanings of \( I \), \( B \), and \( D \) respectively are:
- \( I \): Rate of immigration
- \( B \): Natality rate
- \( D \): Mortality rate

### Final Answer:
- \( I \): Rate of immigration
- \( B \): Natality rate
- \( D \): Mortality rate