In a right-angled triangle, the Pythagorean theorem states that the sum of the squares of the two legs (the height and the base, in this case) equals the square of the hypotenuse.
In this case:
- The height \( S T \) is \( p \).
- The base \( T P \) is \( s \).
- The hypotenuse \( P S \) is \( t \).
According to the Pythagorean theorem, we have:
\[ p^2 + s^2 = t^2 \]
Thus, the correct option is Option 2.
So, the answer is: 2.