Let's verify the ease of hexadecimal-to-binary conversion by working through an actual example rather than just stating the rule.
Take the hexadecimal number \( (2F)_{16} \).
Each hex digit is converted to its 4-bit binary equivalent on its own, independent of the other digits:
\( 2 \) becomes \( 0010 \)
\( F \) (which equals 15) becomes \( 1111 \)
Placing these groups side by side in order gives \( (2F)_{16} = (00101111)_2 \).
Notice that no multiplication, division, or repeated remainder calculation was needed at any stage. Compare this to converting \( (2F)_{16} \) to decimal, where you must compute \( 2 \times 16 + 15 = 47 \), an actual arithmetic operation. The binary conversion instead only required knowing four fixed bit patterns for the digits 2 and F.
This works because \( 16 = 2^4 \), so every possible hex digit (0 through F) has exactly one corresponding 4-bit pattern, and stringing these patterns together reconstructs the binary number exactly, with the reverse process (grouping binary digits into fours) working just as directly.
Therefore, the correct answer is binary.