Final answer:
The sentence "Ella es seria" is correct.
Step-by-step explanation:
The sentence "Ella es seria" is correct. It translates to "She is serious" in English. In Spanish, the subject pronoun 'ella' means 'she' and the verb 'es' means 'is'. The adjective 'seria' means 'serious' and agrees with the feminine subject pronoun 'ella'. Therefore, the sentence is grammatically accurate.
Learn more about Spanish sentence structure