Which one of the following statements is correct? When a fluid passes through the narrow part of non-uniform pipe,

Consider two points A and B in the pipe at the same horizontal level. At point A, let $a_1$ be the area of cross-section of the pipe, $v_1$ the velocity of fluid flow and $p_1$ the fluid pressure. Let $a_2,v_2$ and $p_2$ be the corresponding quantities at point B. Then from Bernoulli's theorem, we have
$$\begin{gathered} p_1+\frac{1}{2}\rho v_1^2=p_2+\frac{1}{2}\rho v_2^2 \\ \text{ or } \left(p_1-p_2\right)=\frac{1}{2}\rho \left(v_2^2-v_1^2\right) \left(i\right) \end{gathered}$$
If $a_2<a_1$, it follows from continuity equation $a_1{v}_1=a_2{v}_2, that v_1>v_2$.

From Eq. (i), it follows that $p_2<p_1.$ Hence, at the narrow part of the pipe, the fluid velocity increases but its pressure decreases, which is choice (4).