Question

I produce food in the plant ____________

Answer 1

chlorophyll.....
Hope it helpled you...

Answer 2

Plants prepare their food in leaves.

Leaves are called as Food factories of plant.

All leaves contain pigment called as Chlorophyll which imparts green colour to leaf. 
By the photosynthesis process, leaves prepare their own food.
Plants need following things to prepare food:
1. sunlight
2. cholorphyll.
3. CO2.
4. Water