The first theory about the structure of an atom was introduced by:

Explanation

The first theory about the structure of an atom was introduced by:(a) Neil Bohr: Neil Bohr, also known as Niels Bohr, proposed the Bohr model of the atom in 1913. According to his model, electrons orbit the nucleus in specific energy levels or shells. This model explained the stability of atoms and the emission and absorption of light.(b) Einstein: While Albert Einstein made significant contributions to the field of physics, he did not introduce the first theory about the structure of an atom.(c) Compton: Arthur Compton was a physicist known for his work on X-ray scattering and the Compton effect, but he did not introduce the first theory about the structure of an atom.(d) Rutherford: Ernest Rutherford is the correct answer. He proposed the nuclear model of the atom in 1911. His gold foil experiment showed that atoms have a small, dense, positively charged nucleus at the center, surrounded by mostly empty space with negatively charged electrons orbiting around it.So, the correct answer is (d) Rutherford.