The 20th century is past - I still can't really believe that this is 2013 - anyway...

The 20th century is past and is not ongoing, so you do not need "has" which is the continuous form.

You also do not need "had" since you are not talking about two different levels of the past. Since you are only talking about 1 level of the past - the 20th century, you can use the simple past and say, as B does, "the growth of democracy generally followed industrial development throughout the 20th century.

Choice A would be correct if this were still the 20th century.

Choice C might work is they also had the 19th century in there to give two levels of the past. Such as "the growth of democracy followed industrial developement in the 20th century just as it had done in the 19th."... something like that. This would require the use of the past perfect "had" to place the action in the 19th prior to that of the 20th.

Hi David,
I have a question about a sentence that you used for the explanation.
You mentioned "Choice A would be correct if this were still the 20th century."

Could you please explain the use of were and was?
I always get confused between were and was.

Thanks

Hi David,
I have a question about a sentence that you used for the explanation.
You mentioned "Choice A would be correct if this were still the 20th century."

Could you please explain the use of were and was?
I always get confused between were and was.

Thanks

Hi David,
I have a question about a sentence that you used for the explanation.
You mentioned "Choice A would be correct if this were still the 20th century."

Could you please explain the use of were and was?
I always get confused between were and was.

Thanks

Hi David,
I have a question about a sentence that you used for the explanation.
You mentioned "Choice A would be correct if this were still the 20th century."

Could you please explain the use of were and was?
I always get confused between were and was.

Thanks