Read the passage and answer the question. "Siti had been preparing for the school science fair for weeks. She had tested her hypothesis five times, recorded her results carefully, and prepared a detailed poster. On the morning of the fair, she felt her heart pounding as she stood beside her project. When the judges arrived at her table, she took a deep breath and began to explain her experiment clearly and confidently." Why did Siti take a deep breath before speaking to the judges?