Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Example Input: Context: From the outside, the skin looks plain and simple, as you can see in Figure 16.5. But at a cellular level, theres nothing plain or simple about it. A single square inch of skin contains about 20 blood vessels, hundreds of sweat glands, and more than a thousand nerve endings. It also contains tens of thousands of pigment-producing cells. Clearly, there is much more to skin than meets the eye! For a dramatic introduction to the skin, watch this video: MEDIA Click image to the left or use the URL below. URL: The skin is only about 2 mm thick, or about as thick as the cover of a book. Although it is very thin, it consists of two distinct layers, called the epidermis and the dermis. You can see both layers and some of their structures in Figure 16.6. Refer to the figure as you read about the epidermis and dermis below. The epidermis is the outer layer of skin. It consists almost entirely of epithelial cells. There are no blood vessels, nerve endings, or glands in this skin layer. Nonetheless, this layer of skin is very active. It is constantly being renewed. How does this happen? 1. The cells at the bottom of the epidermis are always dividing by mitosis to form new cells. 2. The new cells gradually move up through the epidermis toward the surface of the body. As they move, they produce the tough, fibrous protein called keratin. 3. By the time the cells reach the surface, they have filled with keratin and died. On the surface, the dead cells form a protective, waterproof layer. 4. Dead cells are gradually shed from the surface of the epidermis. As they are shed, they are replaced by other dead cells that move up from below. The epidermis also contains cells called melanocytes. You can see a melanocyte in Figure 16.7. Melanocytes produce melanin. Melanin is a brown pigment that gives skin much of its color. Everyones skin has about the same number of melanocytes per square inch. However, the melanocytes of people with darker skin produce more melanin. The amount of melanin that is produced depends partly on your genes and partly on how much ultraviolet light strikes your skin. The more light you get, the more melanin your melanocytes produce. This explains why skin tans when its exposed to sunlight. The dermis is the inner layer of skin. It is made of tough connective tissue. The dermis is attached to the epidermis by fibers made of the protein collagen. The dermis is where most skin structures are located. Look again at Figure pain, pressure, and temperature. If you cut your skin and it bleeds, the cut has penetrated the dermis and damaged a blood vessel. The cut probably hurts as well because of the nerve endings in this skin layer. The dermis also contains hair follicles and two types of glands. You can see some of these structures in Figure 16.8. Hair follicles are structures where hairs originate. Each hair grows out of a follicle, passes up through the epidermis, and extends above the skin surface. Sebaceous glands are commonly called oil glands. They produce an oily substance called sebum. Sebum is secreted into hair follicles. Then it makes its way along the hair shaft to the surface of the skin. Sebum waterproofs the hair and skin and helps prevent them from drying out. Sweat glands produce the salty fluid known as sweat. Sweat contains excess water, salts, and other waste products. Each sweat gland has a duct that passes through the epidermis. Sweat travels from the gland through the duct and out through a pore on the surface of the skin. You couldnt survive without your skin. It has many important functions. In several ways, it helps maintain homeostasis. The main function of the skin is controlling what enters and leaves the body. It prevents the loss of too much water from the body. It also prevents bacteria and other microorganisms from entering the body. Melanin in the epidermis absorbs ultraviolet light. This prevents the light from reaching and damaging the dermis. The skin helps maintain a constant body temperature. It 
 Question: __oily substance secreted by glands in the skin
Example Output: sebum

Example Input: Context: Ali Sadiki (born 10 December 1987) is a Zimbabwean professional footballer, who plays as a defender for TP Mazembe in DR Congo. 
 Question: Which sports team is Ali Sadiki playing for?
Example Output: tp mazembe

Example Input: Context: Where do dogs come from? Gray wolves are their ancestors. Scientists are pretty consistent about that. And researchers have suggested that dogs' origins can date back to Europe, the Near East, Siberia and South China. Central Asia is the newest and best candidate, according to a large study of dogs from around the world. Laura M. Shannon and Adam R. Boyko at Cornell University, and an international group of other scientists, studied not only purebred dogs, but also street or village dogs. Dr. Shannon analyzed three different kinds of DNA, Dr. Boyko said, the first time this has been done for such a large and diverse group of dogs from 38 countries. And that led them to Central Asia as the place of origin for dogs in much the same way that genetic studies have located the origin of modern humans in East Africa. The analysis, Dr. Boyko said, pointed to Central Asia, as the place where "all the dogs alive today" come from. The data did not allow precise dating of the origin, he said, but showed it occurred at least 15,000 years ago. Greger Larson of Oxford University, who is leading a large international effort to analyze ancient DNA from fossilized bones, said he was impressed by the study. "It's really great to see not just the number of street dogs, but also the geographic breadth and the number of remote locations where the dogs were sampled," he said in an email. He also praised the sampling of different kinds of DNA and the analytic methods. Dr. Larson, who was not involved with the study, said he thought the Central Asia finding required further testing. He said he suspected that the origins of modern dogs were "extremely messy" and that no amount of sampling of living populations will be definitive. He said a combination of studies of modern and ancient DNA is necessary. 
 Question: Who wasn't engaged in the study of dogs' origins?
Example Output:
greger larson