If the labor supply curve is very elastic, a tax on laborA. raises enough tax revenue to offset the loss in welfare. B. has a large deadweight loss. C. results in a large tax burden on the firms that hire labor. D. has a relatively small impact on the number of hours that workers choose to work.

.B. has a large dead weight loss

Explanation:

 The labor market basically has two forces pulling against each other, we have firms who demand labor and we have workers who are Suppliers of labor. Firms will want to hire more labor at a lower wage price while more workers will want to work when the wage price is higher as the law of supply stipulates  

The law of supply states that more is supplied at a higher price, now using the same law on the supply of labor we conclude that more labor will be supplied at a higher Wage which represents Price. A Labor Market is equilibrium when Quantity Demanded Equals Quantity Supplied. Elasticity measures the sensitivity of Demand or Supply to Price Changes. The amount of Change in the Quantity supplied or demanded depends on how elastic the demand or supply is to wage Price changes

When Supply Curve is highly elastic means a small change in wage price will have a huge impact on the Total amount Labor supplied. When government imposes Tax on labor, The Wage price will decrease and workers will now earn a wage net of tax,

The Supply curve is highly elastic meaning a small decrease in wages caused by a tax imposed on labor  will only lead to a huge decrease in the quantity of labor supplied because more people will choose not work. The tax imposed on labor creates a huge dead weight loss in the labor market because the market is no longer in equilibrium. The Quantity of labor supplied is far less than the quantity of labor demanded.