The leaves which fall down very soon after their formation are —
A. Deciduous
B. Caducous
C. Evergreen
D. None of the above

Hint: Leaves have their different types according to their duration of survival on the trees. Some shed before their complete development, some shed seasonally and some are seen to grow throughout the year. Climate changes can also influence their growth and duration.

Complete answer:
According to the duration of leaf on the tree, it can be classified into three types namely — deciduous, caducous and evergreen.
Deciduous — “tend to fall off at maturity”. Deciduous leaves are those that tend to fall in one season. It is seen in the month of fall (autumn). Examples — In case of walnuts leaves are seen to drop early and in case of maple they drop in mid november. This leads to decreased photosynthesis. The green color becomes less visible. The colorful pigments become dominant. These contain carotenoids in them which produce yellow, orange and brown color to the leaves.
Caducous means “shedding off at early stage”
Eg— papaver leaves
Evergreen symbolizes immortality. Evergreen leaves are those that have green leaves throughout the year. Climate change does not have any effect on these plants. These maintain their green leaves and stems throughout the year. These grow out till the next season through harsh winters. Examples — conifers (cone bearing plants) are evergreen.

The correct answer to the question is B i.e caducous.

Note: Deciduous leaves are those that shed on maturity. These are seen to shed in fall (autumn).
Caducous leaves are those that shed early than the stage of development. Evergreen leave are those that do not shed throughout the year. They resist winter and grow out in the next season.