By virtue of (its) size and supersensitive electronics, modern radio telescopes are able to gather more waves and (discriminate among) (them) with greater precision (than) earlier versions could. (No error)
Where is the the error here?
is it (its), (discriminate among), (them) or (than)?
the answer says it's (its)
The error is its because it should be their (plural).
their size...radio telescopes