The is the center of a stem and can store food.
a. cortex
b. vascular cylinder
c. pith
d. receptacle

b. vascular cylinder  

The tissues of the vascular system of the plant stem helps in the translocation and storage of the food in the plant. The phloem is the main type of vascular tissue that helps in the distribution of the food from the leaves to different parts of the plant body. These includes sieve tubes, companion cells, phloem parenchyma and phloem fibers. The sieve tubes formed by the cylindrical cells. The terminal walls of these cells exhibit minute pores called as sieve plates. Through sieve plates the food is passed from one cell to the other cells. Companion cells helps in the conduction of the food materials through sieve plates. Phloem parenchyma helps in the storage of food. Phloem fibers helps providing the mechanical support to the plant.

thymine. in rna, thymine is replace by uracil

the answer is d.) homologous; have mammary glands