Correct Answer: A
Explanation:
"Perched" is the only answer choice that makes sense in the sentence, because the sentence informs the reader the cat is sitting somewhere high above the garden, and "perched" means balanced on something or sitting on something. We also know that the cat sat "silently" on the fencepost, so neither "yowled" nor "purred" can be the correct answer, as each of those words describes something or someone making a noise.