The correct option is **C. DNA molecules**. ### Detailed Explanation: 1. **Understanding Inherited Traits**: - Inherited traits are characteristics that are passed from parents to offspring. These traits can include physical attributes like eye color, height, and even certain behaviors. The underlying mechanism for how these traits are passed on is rooted in genetics. 2. **Role of DNA**: - DNA, or deoxyribonucleic acid, is the molecule that carries the genetic instructions for the development, functioning, growth, and reproduction of all known living organisms and many viruses. It is often referred to as the blueprint of life. - DNA is structured as a double helix and is composed of sequences of nucleotides. Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine). The specific sequence of these bases encodes the information necessary to produce proteins, which in turn influence the traits of an organism. 3. **Why Option C is Correct**: - Since DNA contains the genetic information that determines inherited traits, it is the primary molecule responsible for controlling these traits. Genes, which are segments of DNA, provide the instructions for making proteins that affect how an organism looks and behaves. ### Why the Other Options are Incorrect: - **A. RNA molecules**: - RNA (ribonucleic acid) plays a crucial role in the process of translating the genetic information stored in DNA into proteins. While RNA is essential for gene expression, it does not store genetic information itself. Instead, it acts as a messenger and is involved in protein synthesis. Therefore, RNA is not the primary molecule that controls inherited traits. - **B. Nucleotides**: - Nucleotides are the building blocks of DNA and RNA. While they are essential for the structure of these molecules, they do not directly control inherited traits. Instead, it is the sequence of nucleotides in DNA that encodes the genetic information. Thus, nucleotides are components of DNA, but they do not independently control traits. - **D. Enzymes**: - Enzymes are proteins that catalyze biochemical reactions in the body. While they are crucial for various metabolic processes and can influence traits indirectly (for example, by affecting how genes are expressed), they do not carry genetic information. Therefore, enzymes are not responsible for controlling inherited traits. ### Summary of Key Points: - Inherited traits are controlled by **DNA molecules**, which contain the genetic information. - DNA is structured as a double helix and is made up of sequences of **nucleotides**. - **RNA** is involved in protein synthesis but does not store genetic information. - **Nucleotides** are the building blocks of DNA and RNA, while **enzymes** facilitate biochemical reactions but do not control traits. This understanding of DNA's role in genetics is fundamental for anyone studying biology or preparing for exams in related fields.