Which of the following statements regarding option contracts is true? a) One equity put or call option contracts is an option to sell or buy 100 shares. b) Writers of OTC options are required to maintain appropriate margin in their options accounts at all times. c) Only European-style options can be exercised prior to the expiration date. d) Writing an put option has more risk than writing a call option. What margin is required if an investor purchased 5,000 shares of XYZ, a security not eligible for reduced margin, for $25.75 per share? a) $64,375 b) $25,750 c) $90,125 d) $38,625