Tissues combined to form . a. organs
b. an organism
c. cells
d. an organ system

Your answer is A. Organs

Explanation:

molecules combine to form cells, cells combine to form tissues, tissues combine to form organs, organs combine to form organ systems, and organ systems combine to form organisms.

the millers tale is the answer.

atomic number of carbon is 6

electronic configuration of carbon is 1s²2s²2p²

orbital diagram of carbon is as shown here in the image.