The correct answer is 8 bits.
Eight bits make a bye. A bit is a binary digit, and it is the smallest unit of storage on a computer. Bits are so little that they can only hold values of either 0 or 1 (on or off).

A byte is a total of 8 bits. It takes 8 bits which is equal to a byte to store a letter on a computer. Other units of storage include:
A nibble is made up of 4 bits. A Kilobyte is a made up of 1,024 bytes. A megabyte is equivalent to 1,048,576 bytes or about 1,024 kilobytes. Others include Gigabyte, terabyte, petabyte, Exabyte, zettabyte, yottabyte, and so on.

A bit is the smallest unit of storage in the computer world, and it takes eight of them to make a byte, which you would need to store one letter. Ever since computers were introduced the need for storage has increased to epic proportions.

Since 2018 the measurements extend from one bit to the current Yottabyte which will hold five quintillion, thirty-seven quadrillion, one hundred ninety trillion, nine hundred fifteen billion, sixty million, nine hundred fifty-four thousand, eight hundred ninety-four books of 200 pages each. This is a breathtaking figure and will time and progress, and there are two proposed storage units which would be the hellabyte and the brontobyte.