Here, we are asked "magnitude" - so we just need to consider the mantissa bits.
Also, we are told "normalized representation"- so most significant bit of mantissa is always 1 (this is different from IEEE 754 normalized representation where this 1 is omitted in representation, but here it seems to be added on the right of decimal point as seen from options).
So, the maximum value of mantissa will be 23 1's where a decimal point is assumed before first 1. So, this value will be $1-2^{-23}$.
Due to the 1 in normalized representation, the smallest positive number will be 1 followed by 23 0's which will be $2^{-1} = 0.5.$
So ans d.