Answer: B. radio telescopes
Explanation: Radio telescopes are used because of their ability to find radio-frequency radiation. This is perfect for finding black holes because it shows us the beautiful remains of a star as clouds that is called a supernova remnants and sometimes nebulae.
Hope this helps!
A. A pronoun replaces an antecedent.
B. The antecedent of a pronoun is not clear.
C. The pronouns do not agree in number.
D. A pronoun is repeated in a sentence. i think
The Answer is C. The, Dog, Pompeii