Select the most appropriate option to fill in the blank.
I have observed that there is proper natural ____________ even at 6 o'clock on summer mornings.

Correct option is A

Explanation:
• The correct noun is “light”, which refers to daylight or illumination.
• “Gleam” and “sparkle” suggest brief or flickering light and are not suitable in this general context.
Correct: There is natural light even at 6 o'clock…
Option Meanings:
Light – brightness from the sun or artificial sources.
Gleam – a brief or faint shine.
Lucent – adjective, not a noun; means glowing or radiant.
Sparkle – small flashes of light; twinkle.