If a DNA strand contains 12% thymine, it also contains a. 12% A, 38% G, 38% C
b. 12% A, 12% G, 38% C
c. 12% A, 12% G, 12% C
d. 38% A, 12% G, 38% C

If G = 14, then C = 14 and G + C is 28. Thus A + T. The percent of adenine in a double-stranded DNA is 38. Therefore G + C = 100 - 76 = 24, and C = 24/2 = 12 percent.  

Explanation:

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.

c: warm water flows from the western tropical pacific toward south america. that should be the right answer! hope it .