Answer:
b. a collection of 8 binary digits
Step-by-step explanation:
a. is wrong, byte is not a text, can never be a text. A text in your screen is made of bytes, not the other way around. That's like saying "your cells are made of body" No, your body is made of cells.
c. is wrong, same as the above, ascii is made of byte but byte is not the 3-digit ascii system.
d. completely wrong, or else there wouldn't be megabytes, gigabytes, etc.
b. is correct, 1 byte = 8 bits, each bit can take either 1 or 0 as binary values.