Some plant fertilizer compounds are (NH₄) ₃PO₄, H₂SO₄, NH₃, Ca(H₂PO₄) ₂, and H₃PO₄. Which of these compounds contain both ionic and covalent bonds?
A. Ca(H₂PO₄) ₂
B. H₂SO₄
C. NH₃
D. (NH₄) ₃PO₄
E. H₃PO₄