The right option for the statement “Tyndall effect is exhibited by”, is :

The Tyndall effect refers to the scattering of light by particles suspended in a medium, which makes a light beam visible as it passes through the substance.

For the Tyndall effect to occur, the particles must be large enough (typically 1‑1000 nm) to scatter visible light, but still small enough to remain dispersed without settling quickly. Such a system is called a colloid.

Among the given options:

• Starch solution – Starch forms a colloidal dispersion when dissolved in water; the particles are microscopic granules that scatter light, producing a noticeable beam (the classic Tyndall effect).

• Urea solution – Urea dissolves completely to form true molecular solutions; the particles are individual molecules (< 1 nm) that are too small to scatter visible light, so no Tyndall effect is observed.

• NaCl solution – Similar to urea, NaCl creates a true solution of ions, which do not scatter light appreciably.

• Glucose solution – Glucose also forms a true molecular solution; its molecules are too small to cause observable scattering.

Therefore, the only option that exhibits the Tyndall effect is the starch solution.