The factors of \[{{x}^{4}}+{{y}^{4}}+{{x}^{2}}{{y}^{2}}\] are _____.

• A.  \[({{x}^{2}}+{{y}^{2}})({{x}^{2}}+{{y}^{2}}-xy)\]
• B.  \[({{x}^{2}}+{{y}^{2}})({{x}^{2}}-{{y}^{2}})\]
• C.  \[({{x}^{2}}+{{y}^{2}}+xy)({{x}^{2}}+{{y}^{2}}-xy)\]
• D.  Factorisation is not possible