Right option is (a) True
The best explanation: Irreversible inhibition is one in which loss of activity cannot be restored by the removal of inhibitor. Irreversible inhibition behaves as time-dependent loss of enzyme concentration, when the enzyme is totally inactive. In cases involving incomplete activation, there may be time dependent changes in both Km and Vmax. Heavy metal ions such as mercury, lead, etc., cause irreversible inhibition because they strongly bind to the amino acid backbone. Hence they should not come in contact with enzymes.