1. The problem asks about what must be imposed to find a particular solution to a differential equation. 2. In differential equations, general solutions often contain arbitrary constants. 3. To find a *particular solution*, specific values for these constants must be determined. 4. This is done by imposing *conditions* that the solution must satisfy. 5. There are two common types of conditions: *initial conditions* and *boundary conditions*. 6. Initial conditions are values specified at a single point (e.g., the value of the function and its derivatives at $x=0$). 7. Boundary conditions specify values at the boundaries of the interval where the solution is defined. 8. Both types of conditions serve to uniquely determine the arbitrary constants and thus give a particular solution. 9. The options are: a. initial conditions b. ordinary conditions c. undetermined conditions d. boundary conditions 10. Since the question does not specify the type of differential equation or the problem setup, the most general and common answer is: - *initial conditions* (option a) for initial value problems - or *boundary conditions* (option d) for boundary value problems 11. Usually, when simply asked what to impose, the correct answer is **initial conditions** because they are the standard requirement to find a particular solution of an ordinary differential equation. Final answer: a. initial conditions