The correct option is A A moderate increase or decrease of trace elements causes deficiency and toxicity respectively
Micronutrients are required by plants in small quantities. A moderate decrease results in deficiency while moderate increase results in toxicity.
Reduction in the dry weight of tissues by 10% due to a mineral concentration is considered as toxicity caused by that particular mineral. However, the concentration at which this occurs is different for different micronutrients.
Manganese toxicity levels inhibits calcium translocation in the shoot. Hence, manganese toxicity induces deficiency of calcium.
The transport of water with dissolved minerals over long distances occurs via xylem from roots to different parts of plants.