Yes, you can file RTI application to William Carey University to verify your marksheet. The university is established in Meghalaya By an Act of Parliament. It came into existence on 1st March 2005. It is UGC approved university and Established under section 2(f) of UGC ACT 1956. Hence, it is a public authority under section 2 (h) of the RTI Act 2005 and is liable to provide information under section 6(1) and 2 (f).
As per the decision of the Central Information Commission in the case titled Subhash Chandra Tyagi vs CBSE bearing no. CIC/SA/A/2016/001451, it has been held that every person has a right to know the genuineness of his degree and education and hence all qualifying examinations, degrees and marksheets are public information under the RTI Act. So,the application can be made to the designated PIO along with payment of requisite fees and copy of the documents to be verified.
For further assistance to file RTI application for marksheet verification please refer https://onlinerti.com/how-to-file-rti-online-for-marksheet