Final answer:
Callout extensions are short text snippets used in online ads to highlight the features or benefits of a product or service. They are not used for providing contact information or direct interaction like messaging or voice calls.
Step-by-step explanation:
An accurate description of callout extensions is option d) Short, specific snippets of text that highlight value-adding attributes. Callout extensions are used in online advertising, typically seen in search engine ads. They enable advertisers to include additional descriptive text in their ads to showcase unique selling points, services, promotions, or features of their business. For example, an advertiser might use callout extensions to highlight 'Free Shipping', '24/7 Customer Service', or 'Lifetime Warranty'. This feature helps businesses communicate the beneftis of their offerings to potential customers without needing them to click through to the website first.
It's important to note the difference between the various types of ad extensions. For instance, unlike option a) where an ad is extended with a phone number, callout extensions don't include contact information but rather focus on conveying short messages. Considering the behavior of mobile users, as mentioned in the Steele survey, although 54 percent of respondents used their phones for messaging, callout extensions are about quick, informative text rather than interactive communication such as messaging or calls.