Sicilian defence, 2: Paulsen variation

Sicilian Defense - Four Knights Variation - Remote Chess Academy

Sicilian Defense: Full Guide, Main Lines, Secondary Options

Sicilian Defense - How to play, attack, and Counter the Sicilian?

LHow to play the Sicilian Defence! - Elisabeth Pahtz

Master Sicilian Defense Strategy: Your Winning Blueprint - Remote Chess Academy

Sicilian Defense: Old Sicilian Variation

Portisch on the Sicilian Defense: 3 Things to Learn - TheChessWorld

Encyclopaedia: Modern Chess Opening - Sicilian Defence by Alexander Kalinin (editor) - First - 1996 - from The Book Collector ABAA, ILAB, TBA (SKU: BSC0444)

Fighting the Anti-Sicilians: Combating 2 c3, the Closed, the Morra Gambit and other tricky ideas by Richard Palliser – Everyman Chess

I'm trying to understand the Sicilian Defense - Kramnik Variation (1.e4 c5 2.Nf3 e6 3.c4). Can someone, in simple terms, explain to me why Black's response of a forceful d5 is such