Understanding JSX in React

React leverages JSX, a syntax extension for JavaScript, to describe the structure of the user interface. This enriched JavaScript syntax might look like HTML or XML, thereby making it intuitive and easy to create and manage complex UI structures.

Firstly, it's important to clarify that JSX is not faster because it inherently optimizes JavaScript during compilation. This statement could be misleading. Rather, the key point is that React itself performs optimizations, and JSX aids this by improving code readability and maintainability.

Secondly, comprehend that JSX isn't just a "syntax notation for JavaScript XML". In fact, JSX combines the power of JavaScript with the intuitiveness of HTML. It helps to write JavaScript code that seamlessly incorporates HTML-like syntax to describe how the user interface should be rendered. Where standard HTML would use template syntax, JSX uses JavaScript's capabilities, which makes the code more expressive and flexible.

const element = <h1>Hello, world!</h1>;

This simple code snippet illustrates how JSX integrates HTML-like syntax within JavaScript. Here, we are defining a constant 'element' and assigning it an H1 HTML element containing the text "Hello, world".

Thirdly, one of the core benefits of using JSX is indeed the expressiveness it provides by combining JavaScript and HTML, making it much easier to construct complex UIs. One can use JavaScript within curly braces {} in the JSX tags, enabling us to write logic within the UI code itself!

To showcase this feature, let's consider this code snippet:

const name = 'User';
const element = <h1>Hello, {name}</h1>;

In this example, we see that the JSX syntax seamlessly incorporates the JavaScript constant 'name' within an H1 HTML tag.

Therefore, when we say "all the above options" are correct about JSX, we are acknowledging the holistic and intertwined rapport of HTML's intuitiveness and JavaScript's expressiveness provided by JSX.

Having grasped this, it is evident that JSX is not just a key part of React, but a powerful tool for modern web development. Its nature of borrowing the best from both JavaScript and HTML allows developers to write more maintainable and scalable applications with less cognitive load.