Intersection of two prime-heavy sets — compute A ∩ B explicitly: Given A = {2, 3, 5, 7, 11} and B = {1, 3, 5, 7, 9, 11}, determine A ∩ B.

Introduction / Context:
Set intersection retains only elements common to both sets. Here A is a prime list up to 11, while B mixes odds with the prime 11; we simply keep shared elements.

Given Data / Assumptions:

• A = {2, 3, 5, 7, 11}
• B = {1, 3, 5, 7, 9, 11}

Concept / Approach:
A ∩ B = {x : x ∈ A and x ∈ B}. Check each member of A against B to keep the common ones.

Step-by-Step Solution:
2 ∈ A but 2 ∉ B → exclude3, 5, 7, 11 appear in both → includeIntersection = {3, 5, 7, 11}

Verification / Alternative check:
Scan B: {1, 3, 5, 7, 9, 11} → removing 1 and 9 (not in A) leaves {3, 5, 7, 11}.

Why Other Options Are Wrong:
Option A equals A (not intersection); option B equals B; option D and option E introduce elements not present in both sets (2 or 1, 9).

Common Pitfalls:
Confusing union and intersection; forgetting that duplicates do not matter in set notation.

Final Answer:
{ 3, 5, 7, 11 }