Mammals cannot digest cellulose and ttherefore cannot directly obtain glucose from wood. Mushrooms can, however; and some mushrooms use cellulose to make highly branched polymers, the branches of which are a form of glucose called beta-glucans. Beta-glucan extracts from various types of mushrooms slow, reverse, or prevent the growth of cancerous tumors in mammals, and the antitumor activity of beta-glucans increases as the degree of branching increases. These extracts prevent tumor growth not by killing cancer cells directly but by increasing immune-cell activity. Which one of the following is most strongly supported by the information above? ['If extracts from a type of mushroom slow, reverse, or prevent the growth of cancerous tumors in mammals, then the mushroom is capable of using cellulose to make beta-glucans.', 'Any organism capable of obtaining glucose from wood can use cellulose to make beta-glucans.', 'The greater the degree of branching of beta-glucans, the greater the degree of immune-cell activity it triggers in mammals.', 'Mammals obtain no beneficial health effects from eating cellulose.']