Under a "yellow-dog" contract, .
a. employees pledged to refrain from union membership
b. employees had to pay union dues whether or not they were union members
c. employers had to hire employees referred by the union
d. employees had to accept union membership as a prerequisite for employment

Yellow dog contract refers to those contracts, that take place between employer and employees which contains clauses relating to anti-union agreements.

Explanation:

Option A is the correct option that perfectly relates to yellow dog contracts. Employees in an organisation are restricted from entering into any agreements that relates to joining of any union. An employee agree to not to join or enter into any agreements relating to unions and if they do so, they shall resign before joining. they are not allowed ro enter into any such agreements.

i think it can have both positive and negative effects on businesses.

for example:

lets say you own a small business and taxes go up 4% that means it is going to cost your business more money to buy product to sell. but at the same time you make more money from the tax rise.

that is my theory.

anticipatory breach of contract

as the name suggests, an anticipatory breach is a breach of contract before the time of performance. so, if a promisor denies to perform his promise and signifies his unwillingness before the time for performance, then it is an anticipatory breach of contract.

and

actual breach of contract

while an anticipatory breach is before the time of performance, an actual breach of contract is on the scheduled time of performance of the contract. an actual breach of contract can be committed either.

hope this . : )