Final answer:
The correct sentence is option B) A company manufactures and sells x cellphones per week.
Step-by-step explanation:
The correct sentence is option B) A company manufactures and sells x cellphones per week.
Here, the subject is the company, and the verb is 'manufactures and sells'. Since the company is singular, the plural form 'cellphones' should be replaced with the singular form 'cellphone'. Additionally, the word 'per week' should be singular to match the subject.