ANSWER
[tex]P(all-correct)=\frac{1}{3125}[/tex]EXPLANATION
We want to find the probability that the student selects the correct answer on all questions.
For each question, there is only 1 possible correct answer out of 5 options. This means that for each question, the probability of selecting the correct answer is:
[tex]P(\text{correct)}=\frac{1}{5}[/tex]Therefore, for 5 questions (with 5 options each), the probability of selecting the right answer will be the product of selecting the right answer for each of the 5 questions.
That is:
[tex]\begin{gathered} P(all-correct)=\frac{1}{5}\cdot\frac{1}{5}\cdot\frac{1}{5}\cdot\frac{1}{5}\cdot\frac{1}{5} \\ P(all-correct)=\frac{1}{3125} \end{gathered}[/tex]That is the answer.