Explanation

(c)
Zn + 10 HNO_{3} ⟶4Zn(NO_{3})_{2} + NH_{4}NO_{3} + 3H_{2}O
Ammonium
nitrate
$\therefore\$Zn reacts with cold dil HNO_{3}to produce NH_{4}NO_{3}
With dil. HNO_{3} it produces —N_{2}O(nitrous oxide)
With conc. HNO_{3}it produces —NO_{2}(nitrous oxide)