What was it called when both sides fought from behind long ditches they dug with the earth piled in front to protect them?

This is called trench warfare!
The name comes from the trenches, that is the ditches that the soldiers built.

This warfare was typical in the First World War and it led to frequent stalemates: the trenches are easy to defend but hard to attack so for long periods of times the front remained stable.

E) Using credit can decrease the amount of money that will be available to spend in the future.

Explanation:

From the options given above, the one that is not correct is "Using credit card can decrease the amount of money that would be available to spend in the future.

This is because, there is no corelation between use of credit card and the amountof money to be spend in the future. Most times, people usage of credit card  is just for convience sake rather than debit card that is linked to their account.

The amount to be spend if debit card is used is done in credit card while the actual amount would be transfeered from debit card to credit card.