Answer:
c. shift the supply curve of professors to the left ceteris paribus
Step-by-step explanation:
Labour Supply curve shows the labour hours, employees or workers are willing & able to supply, at given wage rates during a period of time.
The curve is upward sloping due to positive relationship between wage rates & labour. As more labour is supplied at higher wage rate, less labour is supplied at lower wage rates.
Change in any other factor other than wages, changes (shifts) the supply curve. Factor increasing labour supply shifts the supply curve rightwards. Factor decreasing labour supply shifts the supply curve leftwards.
The case given : as increase in the minimum qualifying eligibility for the job, decreases the number of people who are 'able' to supply labour as per the criteria. So, it decreases labour supply & shifts the curve leftwards.