B=\(\left(4+\sqrt{15}\right)\left(\sqrt{10}-\sqrt{6}\right)\left(\sqrt{4-\sqrt{15}}\right)\)
=\(\left(4\sqrt{10}+5\sqrt{6}-4\sqrt{6}-3\sqrt{10}\right)\left(\sqrt{4-\sqrt{15}}\right)\)
=\(\left(\sqrt{6}+\sqrt{10}\right)\left(\sqrt{4-\sqrt{15}}\right)\)=\(\left(\sqrt{24-6\sqrt{15}}\right)+\left(\sqrt{40-10\sqrt{15}}\right)\)
=\(\sqrt{15}-3+5-\sqrt{15}=2\)