Magnetic moment of $A^{3+}$ ion is $5.48\times 10^{-23}J/T$.Find out the number of unpaired electrons in it.($9.27\times 10^{-24}J/T$=1BM)

Question

$(a)\;1\qquad(b)\;2\qquad(c)\;4\qquad(d)\;5$