Oh, it marked me wrong for putting "those" so I thought only "these" was correct
I also had "those are my parents" and was marked incorrectly... they should probably accept either answer.
das sind could be eithere "these are..." or "those are...".
The version with "those are..." is currently not accepted.
This is a sentence from the Pearson course; unfortunately, their sentences leak out into the public course (see also https://www.duolingo.com/comment/24066422 ).
Yet another Pearson sentence with a ridiculous English translation given. "That are my parents"?
Yes and no.
English and German work differently here.
As demonstrative determiners before a noun, it's fairly straightforward -- for example, "these houses" = diese Häuser.
One wrinkle is that German doesn't distinguish as strongly as English does between "this/that" or "these/those", and so "these houses" could also be die Häuser or die Häuser hier.
If you know that you are talking about a specific kind of noun, you can often leave out the noun or replace it with a dummy noun "one(s)" in English -- for example, "Do you like my novels? These (ones) are long and that one is shorter" (Magst du meine Romane? Diese (hier) sind lang und der (da) ist kürzer).
But if you're not speaking about specific items from out of a bigger group of items of the same kind, but are introducing something new to the conversation, then German uses neuter singular and has das or dies, regardless of the gender or number of the item(s) you're introducing.
Thus you get Dies sind meine Eltern for "These are my parents", or Das sind meine Eltern.
Using Diese sind meine Eltern would be "These ones are my parents", appropriate only if you had been speaking about a group of "items" (say, "teachers") before and wanted to single out two of them to make a comment about them (that they are your parents). There would be some understood noun which came from context.