Which of the following is correct?
a) in unionized industries, wages are below the level that would prevail in competitive markets.
b) the introduction of a union in an industry reduces the quantity of labor demanded in that industry, causes some workers in that industry to be unemployed, and reduces wages in the rest of the economy.
c) there is a strong consensus among economists that unions are bad for the u. s. economy.
d) all of the above are correct.

There is a strong consensus among economists that unions are bad for the U.S. economy.

Explanation: A union is a group formed by employees of an establishment or workers of the government whose duty is to fight for improved working conditions of its members.

A union can sometimes make unrealistic demands to their employers and also unions tend to shut down economic activities of their sector of operation, if their demands are not met. These factors makes unions partly an economical disadvantage.

1   b) the use of non-standard grammar  

2   a) quiet and shy.