Which of the following groups consists of only micro-nutrients?

The group that consists of only micro-nutrients is "Manganese, molybdenum and zinc". Micro-nutrients are essential elements required by plants in small quantities for their proper growth and development. Manganese, molybdenum and zinc are all essential micro-nutrients that plants need for various functions such as enzyme activation, photosynthesis, and nitrogen fixation. The other options include at least one macro-nutrient, which is an essential element required in large quantities.