Here's a problem to solve: In living things, smaller substances are linked to make up larger substances. Which of the following correctly describes a larger substance made by linking smaller substances?

Among the 4 following options, which is the correct answer?

- A: Nucleotides are linked to make up DNA.
 
- B: Amino acids are linked to make up DNA.
 
- C: Proteins are linked to make up nucleotides.
 
- D: Nucleic acids are linked to make up proteins.
 