Find out whether there is any grammatical error in below sentence.Another reason for pharmaceutical companies beefing up their / OTC (Over the Country) divisions is that prescription drugs with proven safety records which have been reached / the end of the their patent protection periodare

• A. the end of the their patent protection periodare
• B. Another reason for pharmaceutical companies beefing up their
• C. allowed to be sold without a prescription. No error
• D. OTC (Over the Country) divisions is that prescription drugs with proven safety records which have been reached

Answer: (D)