Step 1: Analyzing the Sign Bit.
The sign bit determines whether the number is positive or negative.
\[
0 \Rightarrow \text{Positive Number}
\]
\[
1 \Rightarrow \text{Negative Number}
\]
Since every floating-point number requires a sign indicator, the sign bit is an essential component.
Therefore,
\[
(i)\ \text{is correct.}
\]
Step 2: Analyzing the Parity Bit.
A parity bit is primarily used for error detection during data transmission and memory operations.
Its purpose is to detect accidental changes in stored or transmitted bits.
A parity bit is not part of the mathematical representation of a floating-point number.
Therefore,
\[
(ii)\ \text{is incorrect.}
\]
Step 3: Analyzing the Mantissa (Significand).
The mantissa contains the significant digits of the number and determines the precision of the representation.
For example, in scientific notation:
\[
6.25 \times 10^3
\]
the value \(6.25\) represents the significand or mantissa.
Thus, the mantissa is a mandatory component of floating-point representation.
Therefore,
\[
(iii)\ \text{is correct.}
\]
Step 4: Analyzing the Exponent.
The exponent determines the scale or magnitude of the number.
It specifies how many positions the decimal or binary point should effectively move.
Without the exponent field, very large and very small numbers could not be represented efficiently.
Therefore,
\[
(iv)\ \text{is correct.}
\]
Step 5: Determining the correct combination.
The valid components are:
\[
(i),\ (iii),\ (iv)
\]
Hence, the correct answer is:
\[
{(B)\ (i),\ (iii)\ \text{and}\ (iv)}
\]