If R is the Rydberg’s constant for hydrogen the wave number of the first line in the Lyman series will be

$\frac{R}{4}$ $\frac{3 R}{4}$ $\frac{R}{2}$ 2 R

$\frac{3 R}{4}$

For Lyman series $\bar{v}=\frac{1}{\lambda}=R\left(\frac{1}{1^2}-\frac{1}{n^2}\right)$ here n = 2, 3, 4, 5..... For first line $\bar{v}=R\left(\frac{1}{1^2}-\frac{1}{2^2}\right) \Rightarrow \bar{v}=R\left(1-\frac{1}{4}\right)=\frac{3 R}{4}$