Concept:Nursery operations involve raising and caring for young plants, requiring tools for planting, pruning, and transplanting.
Explanation:Secateurs are used for pruning and cutting small branches in the nursery.
Shears are used for trimming hedges and shaping plants.
A dibber is used to make holes for planting seeds or seedlings.
A sickle is mainly used for harvesting crops or cutting weeds, not for routine nursery operations.
Hence, the tool not used in nursery operations is the sickle.
Answer:B. sickle