In binary number system, the number 100 represents
A. One
B. Three
C. Four
D. Hundred

Hint:This question is based on the binary number to decimal number conversion. You need to follow the rules of conversion here to find out the decimal number for the given binary number.

Complete answer:
For finding binary to a decimal number, you can follow two approaches; we will be calculating the answer from both the methods. The most accurate method of converting the binary into decimal is that we multiply each number of the binary with its place position as a power of 2. The place position is counted from the left, and it starts from zero. We will use it here to find the 100 is represented as what binary number.

The binary number system is very important in computer languages because it stores all numbers in 0 and 1 form. And we process some data; then, the normal number gets converted into the binary one.
Now for the binary system, we can write
$0 = 0$
$1 = 1$
For writing the next number, i.e., 3 in binary, we will start with 0 again but adding 1 to the right Then, $3 = 10$ and so on, we can write the binary for further numbers, but this is a very lengthy way to find the binary number for the decimal number.So for writing 4, we first write the zero then adding 10 to the right of it, i.e. $4=100$

From another method, we multiply each number of the binary with its place position as a power of 2. The place position is counted from the left, and it starts from zero.
So, $100 = 1 \times {2^2} + 0 \times {2^1} + 0 \times {2^0} \Rightarrow 4$
So, the binary number 100 is written 4 in the decimal system.

Hence, option C is the correct answer.

Note:You may go wrong in the question in finding the place value of each digit of a given number because the counting of place value starts from the number 0 and continues further. Place value counting starts from left always.