Answer: Linus Pauling
Explanation: The idea that the four bases in DNA (adenine, guanine, cytosine, and thymine) are stacked like pennies in a precise manner was theorized by Linus Pauling. Pauling was a renowned American chemist and biochemist who made significant contributions to the understanding of the structure of biological molecules, including DNA. He proposed the concept of hydrogen bonding between complementary base pairs and envisioned the bases stacking in a regular manner, similar to how pennies are stacked. This idea was foundational in the development of the model of DNA's double-helix structure.