Read each sentence to find out whether there is any grammatical error in it. The error, if any will be in one part of the sentence. The letter of that part is the answer. If there is no error, the answer is 'D'. (Ignore the errors of punctuation, if any).

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