Ans. a (Lag phase) Ref:Ananthanarayan, 7th ed, p. 19Bacterial growth curve: Growth curve obtained by plotting viable count in relation to time gives bacterial growth curve which shows the following phases;a. Lag phaseb. Log phasec. Stationary phased. Phase of declineLag phase: no increase in number but increase in size of the cells occur. The necessary enzymes & metabolic intermediates are built up in adequate quantitiesLog phase (exponential/ logarithmic): cells start dividing and their no. increases exponentially with time.Stationary phase: cell division stops due to depletion of nutrients and accumulation of toxic products.Viable count becomes stationary as there occurs an equilibrium between dying cells and newly formed cells.Phase of decline: Population decreases due to cell death caused by:1. Depletion of nutrients2. Toxic accumulation3. Autolytic enzymesBacteria with maximum cell size: end of lag phaseSmall, uniform staining cells: log phaseSporulation. storage granules: stationary phaseInvolution forms: stage of decline