In the $2^{\text {nd }}$ harmonic the shape of wave looks like.
The point of touching forms a node point of plucking forms an antinode. Hence, for $2^{\text {nd }}$ harmonic, we need to need wire touched at $\frac{l}{2}$ and pluck it at $\frac{l}{4}$.
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$(A)$ $\beta_2>\beta_1$
$(B)$ $m_1>m_2$
$(C)$ From the central maximum, $3^{\text {rd }}$ maximum of $\lambda_2$ overlaps with $5^{\text {th }}$ minimum of $\lambda_1$
$(D)$ The angular separation of fringes for $\lambda_1$ is greater than $\lambda_2$
