Explanation

(d)
Setting of plaster of Paris is exothermic process
${CaSO}_{4} \bullet \frac{1}{2}H_{2}O\ \overset{\ \ \ \ \ H_{2}O\ \ \ \ \ }{\rightarrow}{CaSO}_{4} \bullet 2H_{2}O\$
orthorhombic
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \overset{\ \ \ \ \ Heating\ \ \ \ \ }{\rightarrow}\ \ \ \ \ {CaSO}_{4} \bullet 2H_{2}O$
mono orthorhombic
gypsum