<prompt> WHO recommended Sampling method for Immunisation coverage evaluationSimple random samplingCluster random samplingStratified random samplingConvenience sampling  <response>: Cluster random sampling CRS Applicable when units of population are natural groups or clusters. Use of CRS in India: Evaluation of immunization coverage. WHO technique used in CRS: 30 x 7 technique total 210 children 30 clusters, each containing 7 children who are 12 - 23 months age and are completely immunized for primary immunization till Measles vaccine. Accuracy: Low error rate of only - 5. Limitation: Clusters cannot be compared with each other. 