PA | Week-6 | Q4

Picked one by one from a mixed channel. Transcript check: both title readers certain; 5 of 5 sampled certain picks confirmed by transcript, none failed. Channel rule: Include only the short pre-recorded worked-solution videos titled like 'Activity N.N (Ques ...)' or 'PA | Week-N | Q...'. Exclude all long live-session recordings (open, TA, revision, practice, 'solve with us' and dated session uploads).