Nonrepudiation means ensuring that a party cannot deny having performed a digital action or transaction. In e-business, contracts and security measures rely on evidence—such as digital signatures that tie an action to a specific user, along with tamper‑evident logs and timestamps—that proof the action happened and who did it. This enduring evidence is what prevents later denial and supports enforceability in disputes or audits. Authentication is about verifying who you are at the moment, confidentiality is about keeping data secret, and availability is about ensuring access to systems. While authentication helps enable nonrepudiation, it isn’t sufficient on its own without the accompanying proof (signatures, logs) that actually ties actions to a person over time.

The central processing unit is the brain of a computer, responsible for executing instructions and coordinating the actions of all other components. It runs the fetch-decode-execute cycle, pulling instructions from memory, figuring out what they mean, and performing the necessary calculations or data movements. This role—actually doing the computing work and directing how data moves through the system—is what makes it the central processing unit. RAM, by contrast, holds data and instructions temporarily for quick access but doesn’t execute them. A video card handles graphics processing, and an optical drive reads and writes discs; neither is the primary engine that runs program instructions. So the term that describes the central processing unit is CPU.

Copyright is the exclusive legal right granted to the creator of original literary, artistic, or musical works to print, publish, perform, film, or record the work, and to authorize others to do the same. This means the owner controls reproduction, distribution, public display or performance, and the creation of derivative works, and can license or restrict those uses. It applies automatically upon creation and lasts for a certain period, protecting the creator’s ability to benefit from their creation. The other terms don’t fit as well: Abstraction isn’t about rights to works, Creative Commons is a licensing framework that lets others use works under specific conditions, and Open Source refers to software licensing that emphasizes free access and modification rather than exclusive control over a broad range of works.

Constant-ratio growth is a hallmark of exponential functions. If you have a function like y = a · b^x, increasing x by 1 multiplies the output by the same amount b, so the ratio y(x+1)/y(x) stays constant. That fixed multiplier is what defines exponential growth. Quadratic growth follows x^2, where the successive ratios aren’t constant—the growth speeds up as x increases. Logarithmic growth rises quickly at first and then levels off, so its consecutive-value ratios change. Reusability isn’t describing a growth pattern of a function. So the term that matches growth with a constant ratio is the exponential function.