In the International System of Units (SI), derived quantities are those that can be expressed in terms of the seven base quantities.
Among the options given:
- Electric current - This is a base quantity (measured in amperes).
- Electric charge - This is also a derived quantity, expressed in coulombs (which is based on the base quantity of electric current).
- Plane angle - This is a derived quantity but is often considered a base quantity in certain contexts (measured in radians).
- Amount of substance - This is a base quantity (measured in moles).
So, the correct answer for which one is a derived quantity in SI units is Electric charge.