Area of spherical triangle
$A = \dfrac{\pi R^2 E}{180^\circ}$
Where
$E = A + B + C - 180^\circ$ → E is called the spherical excess
$E = 123^\circ + 84^\circ + 73^\circ - 180^\circ$
$E = 100^\circ$
$A = \dfrac{\pi(30^2)(100^\circ)}{180^\circ}$
$A = 500\pi \, \text{ m}^2 = 1570.8 \, \text{ m}^2$ Answer: [ B ]