How can you combine flat_map with a condition to extract only even numbers from the sub-arrays?

hard📝 Application Q9 of 15

Ruby - Enumerable and Collection Processing

How can you combine flat_map with a condition to extract only even numbers from the sub-arrays?

arr = [[1, 2], [3, 4], [5, 6]]

Aarr.flat_map { |sub| sub.flatten if sub.include?(2) }

Barr.flat_map { |sub| sub.all?(&:even?) ? sub : [] }

Carr.flat_map { |sub| sub if sub.any?(&:even?) }

Darr.flat_map { |sub| sub.select(&:even?) }

Step-by-Step Solution

Solution:

Step 1: Understand the requirement
We want to extract only the even numbers from each sub-array.
Step 2: Use select inside flat_map
Using select(&:even?) filters even numbers, flat_map flattens them into one array.
Final Answer:
arr.flat_map { |sub| sub.select(&:even?) } -> Option D
Quick Check:
flat_map + select filters and flattens even numbers [OK]

Quick Trick: Use select inside flat_map to filter elements [OK]

Common Mistakes:

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