A slab of $12cm$ thickness and generating heat uniformly at ${10}^6\frac{W}{m^3}$ has thermal conductivity of $200\frac{W}{m}$ degree. Both surfaces of the slab are maintained at $150$ degrees Celsius. Determine the heat flow rate at the quarter planes

$$ a$.30000\frac{W}{m^2}$

b$.,40000\frac{W}{m^2}$

c$.50000\frac{W}{m^2}$

d$.60000\frac{W}{m^2}$