How many carbon atoms combined in the photosynthesis reaction a 12 B2 c6d1

The photosynthesis reaction can be simplified with the following overall chemical equation:

\[ 6 \, \text{CO}_2 + 6 \, \text{H}_2\text{O} \rightarrow C_6H_{12}O_6 + 6 \, \text{O}_2 \]

In this reaction:
- 6 molecules of carbon dioxide (CO₂) contribute a total of 6 carbon atoms.
- The product, glucose (C₆H₁₂O₆), contains 6 carbon atoms.

So, during the process of photosynthesis, 6 carbon atoms are taken in from carbon dioxide and utilized to form one molecule of glucose, which also contains 6 carbon atoms.

Since you mentioned "a 12 B2 c6d1", it seems to be a reference to specific conditions or a study format, but regarding the standard photosynthesis chemical reaction, the key takeaway is that **6 carbon atoms are involved** in the process to produce one molecule of glucose. If there are further details or a specific context needed, please provide that, and I'll be glad to assist!