When we talk about "Big Data" we refer to a$($n$)$

a$.$

set of data so voluminous and complex that it would be very difficult to manage and analyze it using only the traditional information technology systems that companies have as a base.

b$.$

terabyte $(1$ TB$)$ of data.

c$.$

application that serves to analyze a large set of data to support decision making, but only in the field of accounting.

d$.$

voluminous set of qualitative and unstructured data.