Select the most appropriate word to Fill in the blank
Today computer viruses spread ______ a dizzying speed ______ way of file downloads.

Options

A. in, from
B. at, from
C. by, by
D. at, by

Explanation

We use preposition ‘at’ after spread to show the pace at which something is happening. For example, Corona virus is spreading at a rapid(fast) rate across the globe. Similarly in this sentence, ‘at’ will be used to describe the dizzy speed at which the computer viruses are spreading. However, we use by + noun to describe how someone travels or communicates, or how things are processed. Similarly in the given question, by will be used to describe how viruses are spreading by file downloads. Hence, ‘At, By’ will be the most appropriate answer.