Final answer:
The correct verb to use is estar.
Step-by-step explanation:
The correct verb to use in the given sentence is estar.
In Spanish, both ser and estar are verbs that mean 'to be,' but they are used in different contexts. Ser is used to talk about permanent or inherent characteristics, while estar is used to talk about temporary states or conditions. When describing someone's emotion or mood, we use estar.
For example, 'Mi hermano está contento' means 'My brother is happy,' expressing a temporary state of being.