According to the formula,

The average of 1 to n odd numbers =$\frac{\mathrm{Last} \mathrm{odd} \mathrm{number}+1}{2}$

Here, The last odd number= 99

∴ Average of 1 to 99 odd numbers =$\frac{99+1}{2}=\frac{100}{2}=50$

Again, According to the formula,

The average of 1 to n even numbers=$\frac{\mathrm{Last} \mathrm{even} \mathrm{number}+2}{2}$

Here, Last even number = 98

∴ Average of 1 to 44 even numbers =$\frac{98+2}{2}=\frac{100}{2}=50$

Hence, Option A is correct.