Assertion : -Assimilatory roots can photosynthesize
 Reason :- Assimilatory roots possess chlorophyll
A) If both the assertion and the reason are true and the reason is a correct explanation of the assertion .
B) If both the assertion and the reason are true but the reason is not a correct explanation of the assertion.
C) If the assertion is true but the reason is false.
D) If both the assertion and reason are false .

Hint:Assimilatory roots grow on the surface of the leaves and helps in vegetative propagation. Example -: Bryophyllum. These are green, aerial, adventitious roots which prepare food materials by photosynthesis.

Complete answer :
The root is the underground part of the plant that absorbs water and minerals from the soil and anchors the plants firmly. In some plants, the roots change their shape and get modified to absorb and transport water and minerals from the soil to different parts of the plant. They are also modified for support, food storage and respiration.
Assimilatory roots are a type of modified roots. These roots grow chlorophyll and turn into photosynthesis. They synthesize carbon dioxide, water and carbohydrates in the presence of life. Examples of assimilatory roots are Trapa, Taeniophyllum and Tinospora.

Thus, the correct option is A i.e., If both the assertion and the reason are true and the reason is a correct explanation of the assertion .

Notes:Assimilatory roots are also called as photosynthetic roots. In some epiphytes like Taeniophyllum, the stem and leaves are absent. The entire plant is represented by thin green, ribbon-like roots which contain velamen.