Answer: Singular.
Explanation: when writing any sentence, we need to make sure to follow the subject-verb agreement. Subject-verb agreement simply means the subject and verb must agree in number (both need to be singular or both need to be plural). So if we have a singular subject (for example: he, she, it, the dog, the flower, etc), we have to use a singular verb (for example: he runs, the dog barks, etc).
