• Complete Selection Against Recessive Lethal Alleles:
• Initial genotype frequencies under Hardy-Weinberg equilibrium: $AA (p^2), Aa (2pq), aa (q^2)$.
• When all homozygous recessive individuals ($aa$) are completely eliminated ($s = 1$), the surviving breeding population consists only of $AA$ and $Aa$:

• Frequency of Allele A in Next Generation ($p_1$):
• The surviving gametes producing allele $A$ come from $AA$ (weight $p^2$) and $Aa$ (weight $\frac{1}{2}(2pq) = pq$):

• Change in Recessive Frequency ($\Delta q$):
• $q_1 = \frac{q}{1 + q} \implies \Delta q = q_1 - q = -\frac{q^2}{1 + q}$.
• In the options, Option 3 corresponds to the formula with denominator $(1 + q)$.
• Conclusion: Matches Option 3.

Correct option: (3) -7/ (1+ 4)