Which of the following best describes how to pass data from a parent to a child in React?

Which of the following best describes how to pass data from a parent to a child in React?

• A. By mutating the child's internal state.
• B. By rendering the child and passing props in the JSX element.
• C. By using the child as a global variable.
• D. By applying a CSS class to the child.

Answer: (B)

In React, data moves from a parent to a child through props. The parent decides what data to give the child and passes it when rendering the child in JSX, for example by writing something like <Child data={value} />. The child then receives that data in its props and can use it to render or compute something. This one-way data flow helps keep components predictable and easy to reason about. It’s important that a parent doesn’t try to mutate the child’s internal state directly. If the parent needs to update what the child shows, it should pass a new prop or the child can notify the parent via a callback so the parent can update state and re-render. Using the child as a global variable or applying only a CSS class on the child won’t transfer data; those patterns don’t provide a data connection between components.

In React, data moves from a parent to a child through props. The parent decides what data to give the child and passes it when rendering the child in JSX, for example by writing something like . The child then receives that data in its props and can use it to render or compute something. This one-way data flow helps keep components predictable and easy to reason about.

It’s important that a parent doesn’t try to mutate the child’s internal state directly. If the parent needs to update what the child shows, it should pass a new prop or the child can notify the parent via a callback so the parent can update state and re-render. Using the child as a global variable or applying only a CSS class on the child won’t transfer data; those patterns don’t provide a data connection between components.