Answer:
All real number greater than equal to zero.
Explanation:
The function is given by
![f(x) = (4)/(5)\sqrt x](https://img.qammunity.org/2022/formulas/mathematics/college/a2mil1f2j9ifox6uexe77weejbe0sm5pb4.png)
The domain is defined as the input values so that the function is well defined.
here, the values of x should be all real number and zero also.
So, the correct option is (d).