In which one pair, both the plants are commonly vegetatively propagated by leaf pieces?
Leaves of many plants have adventitious buds growing on their leaves which help in vegetative propagation. Eg:- Bryophyllum and Kalanchoe.
Agave and Dioscorea are vegetatively propagated through bulbils (the fleshy buds found in the floral axis that takes park in vegetative propagation).
Chrysanthemum is vegetatively propagated through underground stem modification called suckers which develop from the axil of the scale leaf in the underground part of the stem. They grow horizontally below the soil for some time and then come above the soil and produce aerial shoots.
Asparagus is vegetatively propagated through the formation of adventitious buds on their roots which are capable of giving rise to a new plant.