A survey of how children spend their pocket money found that a sizable amount of it is spent on sweets, snacks and fizzy drinks. The study was based on 4,000 children who were asked to keep a diary of their purchases over a two-year period. On average the children spent $23 a week and over a third of this was spent on sugary and fatty food and drinks. The survey found marked differences in spending trends in sex and age. Boys spent less on clothes, shoes and toiletries and more on games, computer-related items and hobbies. The biggest spenders where children aged 13 to 15 years. The children spent equal sums on mobile phones and charges, and activities and objects that could be classed as educational. Both sexes spent equal amounts on music, but boys spent more on sporting activities.

Question: The passage does not allow the reader to infer the amount children spend on books.
Options:
A. true, B. false, C. uncertain
Answer: "A"