How many atmospheres of pressure are equivalent to one atmosphere?

The concept of atmospheric pressure is fundamental in diving and physics. One atmosphere of pressure is the standard unit of measurement for atmospheric pressure at sea level. Regardless of context or circumstance, one atmosphere is always equal to one atmosphere.

The essence of this question is understanding that atmospheric pressure is constant and does not change based on environments or depths in a linear fashion. Therefore, when considering the question about equivalency, it reaffirms that one atmosphere of pressure is simply defined as itself.

The other choices might imply a misunderstanding of what an atmosphere represents. Only one atmosphere equals one atmosphere, and no multiples of it can redefine its value. Hence, the choice that encompasses multiple statements ultimately acknowledges that they converge on the same truth: one atmosphere is one atmosphere.