Answer:
c. Smart refrigerator reviews
d. Energy-efficient fridge
Step-by-step explanation:
When optimising adverts for search engines, keywords are used. Keywords are those words that people regularly use when searching for a particular item online.
HHA used the keyword refrigerator.
Negative keywords are those that we do not want our adverts seen when they are used. For example HHA used WidgetCo as negative keyword. Anyone that searches WidgetCo will not get the HHA advert. This is a way to avoid paying for clicks that originated from your competitor's search. Most people that search for WidgetCo will not want to buy from HHA.