<prompt> The commonest method of detection of diphtheria carriers is:Schick testDick testCasonis testCharles test  <response>: Schick test, method for determining susceptibility to diphtheria; it laid the basis for inoculation against the disease. A minute amount of diphtheria toxin is injected into the skin of the forearm. Redness at the site of injection after three days indicates a positive reaction absence of circulating antibody or a false positive reaction hypersensitivity to the toxin. A positive reaction can be distinguished by use of a control injection of the same amount of heated toxin toxoid into the other forearm. 