Explanation:

Let's break down the sentences and evaluate the options to find the correct order:

- Statement c: "Nick Vujicic was prevented from" introduces the subject, Nick Vujicic, and suggests a restriction.

- Statement d: "attending mainstream middle schools." completes the meaning of statement c, describing what Nick was prevented from doing.

- Statement a: "However, through sheer grit and determination" offers a contrast or solution to the issue presented in statements c and d.

- Statement b: "Nick was able to get admission to a high school" concludes the narrative, showing the outcome of Nick’s determination.

Now, let's review the options:

- Option 1 (d, c, a, b): Incorrect order - doesn't establish a coherent narrative.

- Option 2 (a, b, c, d): Incorrect order - the solution appears before the problem.

- Option 3 (b, c, a, d): Incorrect order - starts with an outcome.

- Option 4 (c, d, a, b): Correct order - logically flows from the problem (c and d) to the solution (a and b).