To find the number of graduates in the organization, follow these steps:

1. Determine the Total Number of Employees:

Let \( T \) represent the total number of employees.

- 40% of the employees are matriculates:
\[
\text{Number of matriculates} = 0.40 \times T
\]

- Remaining employees:
\[
\text{Remaining employees} = T - 0.40T = 0.60T
\]

- 50% of the remaining employees are graduates:
\[
\text{Number of graduates} = 0.50 \times 0.60T = 0.30T
\]

- The remaining employees are postgraduates, and the number of postgraduates is 180:
\[
\text{Number of postgraduates} = 180
\]

2. Find the Remaining Percentage of Employees:

The remaining employees, who are postgraduates, can be expressed as:
\[
\text{Number of postgraduates} = 0.60T - 0.30T = 0.30T
\]

Therefore:
\[
0.30T = 180
\]

Solving for \( T \):
\[
T = \frac{180}{0.30} = 600
\]

3. Calculate the Number of Graduates:

- Number of graduates:
\[
\text{Number of graduates} = 0.30T = 0.30 \times 600 = 180
\]


The number of graduates is 180.

The correct answer is C. 180.