Context : PetroChina Company Limited (simplified Chinese: 中国石油天然气股份有限公司; traditional Chinese: 中國石油天然氣股份有限公司; Uyghur: چوڭگو نېفتى‎) is a Chinese oil and gas company and is the listed arm of state-owned China National Petroleum Corporation (CNPC), headquartered in Dongcheng District, Beijing. 
Answer : China National Petroleum Corporation
Which company is the parent company of PetroChina?