Am I right? Please someone help me

A. 17,100

Explanation:

The half life of carbon-14 is around 5,700 years. When the shell contains 50% of its original carbon-14, 5,700 years have passed. 25% means another 5,700 years have passed, meaning 11,400 years in total have passed. 12.5% means another 5,700 years have passed, meaning 17,100 years have passed in total.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.

1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint