Chiral carbons have four different substituents

Steps:

• Draw the structure: pentane chain C1–C2–C3–C4–C5 with two methyls on C2, two methyls on C4, OH on C3.
• Analyze C3: attached to H, OH, -C(CH3)3 (left), -C(CH3)2CH3 (right, distinct due to branching).
• Analyze C4: attached to H, CH3 (branch), CH3 (C5, but distinct in context), -CH(OH)C(CH3)3 (chain).
• Confirm no other carbons qualify; total two chiral centers.

Why B is correct:

• By definition, a chiral carbon is a tetrahedral atom bonded to four different groups; C3 and C4 each meet this, giving two chiral carbons.

Why the others are wrong:

• A: Misses the second chiral carbon at C4.
• C: Includes nonexistent third center.
• D: Overcounts; only two qualify.

Final answer: B