The group of chemicals used as pesticide is :

<p>To find out which group of chemicals is used as a pesticide, let&#39;s examine each option :</p> <p>Option A :</p> <ul> <li>Dieldrin : a pesticide</li> <li>Sodium Arsinite : a pesticide and herbicide</li> <li>Tetrachloroethene (also known as perchloroethylene) : used mainly as a solvent and not as a pesticide.</li> </ul> <p>Option B :</p> <ul> <li>Aldrin : a pesticide</li> <li>Sodium Chlorate : mainly used as a herbicide, not a pesticide.</li> <li>Sodium Arsinite : a pesticide and herbicide</li> </ul> <p>Option C :</p> <ul> <li>DDT (Dichloro-Diphenyl-Trichloroethane) : a well-known pesticide</li> <li>Aldrin : a pesticide</li> </ul> <p>Option D :</p> <ul> <li>Sodium Chlorate : mainly used as a herbicide, not a pesticide.</li> <li>DDT : a pesticide</li> <li>PAN (Peroxyacetyl Nitrate) : not used as a pesticide, it is a pollutant found in smog.</li> </ul> <p>From the options given, it appears that Option C (DDT and Aldrin) contains chemicals exclusively used as pesticides. Both chemicals in this option are known pesticides, while the other options contain chemicals that are not used as pesticides or are used for other primary purposes. Hence, the correct answer would be :</p> <p>Option C : DDT, Aldrin</p>