At one time, computers were met with objections from labor unions that they would undermine the workforce, ultimately replacing people and ultimately costing jobs. This is an example of:

Cultural Lag.

Explanation:

Cultural Lag can be defined as the inability of society to pace with changes that occur in the society. This may not necessarily be, but often, is with technology.

In other words, cultural lag or also known as culture lag is the event that happens in the social system when regular ideals of the society are unable to walk with the technological changes.

The term 'cultural lag' was coined by William F. Ogburn. In his book "Social Change With Respect to Culture and Original Nature", he wrote about this concept of cultural lag. He asserted that there is a conflict when there is a gap innovation and adaptation.

The objections for computers by labor union is such an example of cultural lag, mentioned in the question above. This is an example of a cultural lag of the twentieth century.

So, the correct answer is cultural lag.