Final answer:
Dalton's and Democritus' beliefs were similar in that they both considered atoms to be the smallest, indivisible, and indestructible units of matter.(option a)
Step-by-step explanation:
John Dalton and Democritus both contributed significantly to our understanding of atoms. The similarity in their beliefs about atoms lies in the idea that atoms are the smallest unit of matter. The correct answer to the question of how Dalton's and Democritus' beliefs about atoms were the same is: a) They both believed atoms were indivisible and indestructible. Democritus, one of the earliest philosophers to propose the concept of the atom, considered them to be indivisible and indestructible.
Similarly, Dalton's atomic theory also postulated that elements are composed of tiny indivisible particles called atoms. Although we now know that atoms can be split into subatomic particles - protons, neutrons, and electrons - the foundational belief shared by both Dalton and Democritus was that atoms were the smallest indivisible units that composed all matter.
Hence, the answer is option a