In determining the locality of profits, which of the following activities is/are regarded as manufacturing operations according to Departmental Interpretation and Practice Notes No. 21 (Revised)? 1. The employment of labour. II. The use of machinery and plant. III. The design of products. IV. The procurement of raw materials. Select one: O a. I and II only. O b. I, II, III and IV. O c. I only. O d. I, II and III only