Which of the following have the dimension [L¹] ?

The correct answer is option 4) i.e. All of the above

CONCEPT:

• ​Fundamental quantity: A quantity that can be measured is called a physical quantity. 
  • Fundamental quantities are those which cannot be expressed or measured in terms of other physical quantities. 
• The seven fundamental quantities along with their dimensions are as follows:

EXPLANATION:

• A light-year is a distance travelled by light in one year.
• Wavelength is the distance between successive crests or troughs of a wave.
• Displacement is the shortest distance between two points.
• These are all measurements of length and thus, they all have the same dimension i.e. [L¹]