Observe: Scandium is the first element to contain electrons in the d subshell. How many orbitals does the d subshell have, and how many electrons can fit in the d subshell?

5 orbitals

Explanation:

Each d subshell has 5 orbitals, with 10 electrons. So it's like for every orbital, there are 2 electrons. Look at orbital diagrams (if your teacher made you draw them), and you will see that an arrow pointing both UP AND DOWN represent 2 electrons (arrow upward=1 electron, arrow downward=1 electron)