<p style="">The correct answer is (C) well.</p><p style="">Here's why:</p><p style="">(A) "very" is an adverb that is commonly used for emphasis, but it doesn't convey the substantial degree by which the stocks' selling price was below market value.</p><p style="">(B) "so" is an adverb often used to emphasize an outcome ("so" that), and it's typically followed by an adjective and "that" clause. It's not appropriate here because there's no outcome or result clause ("that") after it.</p><p style="">(C) "well" can function as an adverb meaning 'to a great degree or thoroughly' and is often used to show that something is more than usual or expected, which fits the context here. It suggests that the stocks were sold not just below but significantly below the market value.</p><p style="">(D) "such" is an adjective used to emphasize the extent or degree of something, usually followed by a noun or a "that" clause, and it doesn't fit grammatically in this sentence structure.</p>