An electron diffraction pattern was obtained from a pure metal, polycrystalline specimen $($see below$).$

What is likely to be the crystal structure of this specimen? SC$,$ FCC or BCC$?($hint: you can use the table in

class #$22)$

$\frac{R_2}{R_1}=1\mathrm{.}16$

$\frac{R_3}{R_1}=1\mathrm{.}6$

$(2)$