1+4+21+16=\sqrt{1+{\sqrt{4+\sqrt{{21}+{\sqrt{16}}}}}}=1+4+21+16= A4B2C3D6Answer: B. 2 Read Explanation: 1+4+21+16\sqrt{1+{\sqrt{4+\sqrt{{21}+{\sqrt{16}}}}}}1+4+21+16 =1+4+25=1+9=4=2=\sqrt{1+{\sqrt{4+\sqrt{{25}}}}}=\sqrt{1+{\sqrt{9}}}=\sqrt4=2=1+4+25=1+9=4=2 Read more in App