The correct answer is C. Only I and II are implicit.
The statement is an advertisement for Z-T.V., which claims to be the only TV that allows viewers to watch two programs simultaneously. This statement does not provide any information about the current sales of Z-T.V., so it is impossible to say whether or not the advertisement will increase sales. However, the statement does suggest that some people may be influenced by the advertisement and buy Z-T.V., as it highlights the unique feature of the product. Additionally, the statement does not provide any information about the overall trend in sales of Z-T.V., so it is impossible to say whether or not the sales are on the downward trend. Therefore, only assumptions I and II are implicit in the statement.