Plants need green leaves to make food. A plant needs sunlight and carbon dioxide  from the air for making food and it also needs water and salts from the soil to make food too. There are certain cells   in the leaves which change carbon dioxide and water into sugar. To do this the cells needs energy, which they get from the sunlight. Green leaves make food for the whole plant. A red leaf can make food too because under the red color1ing of the leaf there are food----making cells. There are no leaves which are completely yellow, for they can't make food. The plant makes sugar for its food. In sunlight green leaves make a lot of sugar. The veins   can't carry all this sugar away, so the leaves change the sugar into starch  , which is kept and so stored in the leaves. At night, the starch changes back to sugar. It is then carried away from the leaves. Some of the sugar is used as food by the plant while the rest is stored as starch. In some plants, food is stored in the roots, in others it is stored in the stem   and in leaves, fruits and seeds. The cells in the green leaves can get the most energy when   _  .
it is daytime it is night it is sunny it is rainy
Question: Plants need green leaves to make food. A plant needs sunlight and carbon dioxide  from the air for making food and it also needs water and salts from the soil to make food too. There are certain cells   in the leaves which change carbon dioxide and water into sugar. To do this the cells needs energy, which they get from the sunlight. Green leaves make food for the whole plant. A red leaf can make food too because under the red color1ing of the leaf there are food----making cells. There are no leaves which are completely yellow, for they can't make food. The plant makes sugar for its food. In sunlight green leaves make a lot of sugar. The veins   can't carry all this sugar away, so the leaves change the sugar into starch  , which is kept and so stored in the leaves. At night, the starch changes back to sugar. It is then carried away from the leaves. Some of the sugar is used as food by the plant while the rest is stored as starch. In some plants, food is stored in the roots, in others it is stored in the stem   and in leaves, fruits and seeds. The cells in the green leaves can get the most energy when   _  .
A. it is daytime
B. it is night
C. it is sunny
D. it is rainy
Answer: