Question: Whistle and Yodel both specialize in what service?

Context:
Media monitoring service
A media monitoring service, a press clipping service or a clipping service as known in earlier times, provides clients with copies of media content, which is of specific interest to them and subject to changing demand; what they provide may include documentation, content, analysis, or editorial opinion, specifically or widely.
 These services tend to specialize their coverage by subject, industry, size, geography, publication, journalist, or editor.
 The printed sources, which could be readily monitored, greatly expanded with the advent of telegraphy and submarine cables in the mid- to late-19th century; the various types of media now available proliferated in the 20th century, with the development of radio, television, the photocopier and the World Wide Web.
 Though media monitoring is generally used for capturing content or editorial opinion, it also may be used to capture advertising content.
Travel agency
A travel agency is a private retailer or public service that provides travel and tourism related services to the public on behalf of suppliers such as activities, airlines, car rentals, cruise lines, hotels, railways, travel insurance, and package tours.
 In addition to dealing with ordinary tourists most travel agencies have a separate department devoted to making travel arrangements for business travelers and some travel agencies specialize in commercial and business travel only.
 There are also travel agencies that serve as general sales agents for foreign travel companies, allowing them to have offices in countries other than where their headquarters are located.
Bike rental
A bike rental or bike hire business is a bicycle shop or other business that rents bikes for short periods of time (usually for a few hours) for a fee.
 Most rentals are provided by bike shops as a sideline to their main businesses of sales and service, but some shops specialize in rentals.
Airpac Enterprises
Airpac Enterprises, Inc., commonly known as Airpac, is a United States company based in California in the vicinity of Sylmar, known for their airline seat and aircraft overhaul.
 The company provides fully merged aircraft maintenance, repair, and operations (MRO) and interiors services for all kind of airline operators.
 Airpac is a licensed and authorized portion of 145 FAA and EASA repair service by Federal Aviation Regulations.
 Their refurbishment services include tray tables, arm caps, carpet serging, painting, and components.
 They specialize in Avio, BE Aerospace, Embraer, Ipeco, Koito, Recaro, Sicma, Sogerma, and Zodiac Seats.
 The company was founded in 1995 by Nikola Rajic as a small shop in Van Nuys, California, and is today a certified SBO and WBE corporation.
Whistl
Whistl, formerly TNT Post UK, is a postal delivery company operating in the United Kingdom.
 The company primarily competes with UK Mail, UPS, Parcelforce, DHL, Hermes, Royal Mail and Yodel.
 It processes about 25% of the UK's mail, amounting to over 4 billion items per year in 2015.
Yodel (company)
Yodel is a delivery service company in the United Kingdom and is one of the largest couriers along with Royal Mail.
 It was originally known as the Home Delivery Network until it acquired the B2B and B2C operations of DHL Express UK and thereafter, re-branded itself as Yodel in May 2010.
 It is privately owned by the billionaire Barclay Brothers.
Eloise Gerry
Eloise Gerry (12 January 1885 – 1970) was an influential research scientist whose early 20th century work contributed greatly to the study of southern pine trees and turpentine production.
 Gerry was the first woman appointed to the professional staff of the U.S. Forest Service at the Forest Products Laboratory, and one of the first women in the United States to specialize in forest products research.
FinecoBank
FinecoBank () is an Italian financial service company that specialize in online brokerage.
 Founded as a subsidiary of Fineco (itself a subsidiary of Capitalia), the bank became a subsidiary of UniCredit after Capitalia was acquired in 2007.
 In 2016 UniCredit sold 20% shares to public market.
 It became a listed company since 2014.
Jimmie C. Holland
Jimmie C. Holland (b 1928) is a founder of the field of psycho-oncology.
 In 1977, she worked with two colleagues to establish a full-time psychiatric service at Memorial Sloan Kettering Cancer Center.
 The program was one of the first of its kind in cancer treatment, and trained its psychologists to specialize in issues specific to people with cancer.
Corner Bakery Cafe
Corner Bakery Cafe is an American chain of cafes that specialize in pastries, breads, breakfast dishes, gourmet sandwiches, homemade soups, salads, and pasta.
 Corner Bakery Cafe is considered to be a part of the fast casual market segment of the food service industry, offering a somewhat higher quality of food and atmosphere than a typical fast food restaurant, and offering limited table service.

Answer: delivery service company