$\displaystyle{2}{{x}}^{{2}}{{y}}^{{4}}{{z}}^{{2}}{\left({13}{x}+{7}{{y}}^{{2}}{{z}}^{{2}}\right)}={26}{{x}}^{{3}}{{y}}^{{4}}{{z}}^{{2}}+{14}{{x}}^{{2}}{{y}}^{{6}}{{z}}^{{4}}\ne{26}{{x}}^{{3}}{{y}}^{{4}}{{z}}^{{2}}+{14}{{x}}^{{2}}{{y}}^{{6}}\usepackage{cmbright}\Huge\$ so the factorization in item B is not correct.