Hunger signs in plants are
Symptoms due to lesser water absorption in plants
Symptoms due to poor photosynthesis in plants.
Deficiency symptoms of particular mineral nutrients
Symptoms due to excess water absorption in plants.
According to the criteria of essentiality, there are 16 essential elements for plant growth. Hunger signs are shown by plants due to the deficiency of one or more of these mineral nutrients.
So, the correct option is 'Deficiency symptoms of particular mineral nutrients'. Hence, the correct answer is option 3.