Answer:
Option C.
Explanation:
Two beauticians Lydia and Jackie are working on your hair.
Lydia takes the time to complete the work = 2 hours
Per hour work done by Lydia = 1/2
Jackie complete the work = 1 hour
In one hour total work done by both Jackie and Lydia together =

therefore, time taken by both to complete the work will be =
=

Option C. two thirds is the correct option.