Oracle Exam 1Z0-071 Topic 10 Question 41 Discussion

Examine this partial query:

SELECT ch.channel_type, t.month, co.country_code, SUM(s.amount_sold) SALES

FROM sales s, times t, channels ch, countries co

WHERE s.time_ id = t.time id

AND s.country_ id = co. country id

AND s. channel id = ch.channel id

AND ch.channel type IN ('Direct Sales', 'Internet')

AND t.month IN ('2000-09', '2000-10')

AND co.country code IN ('GB', 'US')

Examine this output:

Which GROUP BY clause must be added so the query returns the results shown?