Both X and Y.

X only

Y only.

Neither X nor Y

Its demand for labour is a derived demand

Its demand for labour depends on the marginal revenue product of the labour concerned

If the prices of other inputs that are used along with the labour increase, the firm would be sure to demand less labour

If labour became more productive, the firm would be sure to demand less labour

X has lower transfer earnings than Y

Because Y is earning some economic rent, the firm which hires Y could reduce the wage and Y would continue to work for that firm

If the wage for roofers generally fell enough to persuade Y to take up another occupation, X might continue to be a roofer

If we add up X’s economic rent and transfer earnings, we would get the same figure we would get if we add up Y’s economic rent and transfer earnings

Those with high wages which compensate them for unpleasant aspects of their jobs

Those with high wages which result from them possessing the innate ability to develop some skill to a very high level

Those with low wages which can be paid because their jobs have other very pleasant aspects

Those with low wages which result from no need to have a period of training

The employer is called a monopsonist

The employer faces an upward sloping supply curve for labour, which is also the average cost of labour, ACL

The employer hires more labour so long as the MP of that labour exceeds the marginal cost of that labour, MCL

The wage paid equals the MP of the labour hired