Step 1: Understand the question.
The question describes advertising used when a product is launched for the first time. The aim of such advertising is to tell people that the product exists, what it does and where to get it.
Step 2: Recall the key idea.
Advertising is often grouped by purpose. Informational (pioneering) advertising builds awareness and explains a new product. Persuasive advertising comes later, when rivals are present, and reminder advertising keeps a known brand in mind.
Step 3: Check option 1, Institutional ads.
Institutional ads promote the image and reputation of an organisation, not a specific new product. So option 1 is wrong.
Step 4: Check option 2, Cooperative ads.
Cooperative ads are paid for jointly, for example by a manufacturer and a local retailer. This describes who pays, not a launch purpose. So option 2 is wrong.
Step 5: Check option 3, Informational ads.
Informational ads give facts about a new product, such as features, uses and price, so that the market learns about it. This matches a first-time introduction. So option 3 is right.
Step 6: Check option 4, Cross promotion.
Cross promotion means two brands promote each other's products. It is not tied to introducing a product. So option 4 is wrong.
Final Answer:
A product that is new to the market needs informational advertising to create awareness. This is option 3.
\[ \boxed{\text{Informational ads (Option 3)}} \]