The correct answer is option 1, which states that the nucleus of a singly ionized carbon atom contains 6 protons and 6 neutrons.

To understand this, let`s break down the composition of an atom. An atom consists of a positively charged nucleus at its center, surrounded by negatively charged electrons. The nucleus is made up of protons and neutrons.

Protons are positively charged particles, while neutrons have no charge and are neutral. The atomic number of an element represents the number of protons in its nucleus. In the case of carbon, its atomic number is 6, which means it has 6 protons.

Neutrons, on the other hand, contribute to the mass of the nucleus but do not affect the atom`s charge. So, the number of neutrons can vary for a given element. In this case, the question specifies that the carbon atom is singly ionized, meaning it has a positive charge. However, the question does not provide any information about the number of electrons, which are responsible for the overall charge of the atom.

Therefore, the only information we can be certain about is the composition of the carbon atom`s nucleus, which consists of 6 protons and 6 neutrons.