38. Which of the following best describes why e-mail spoofing is easily executed? a. SMTP lacks an adequate authentication mechanism. b. Administrators often forget to configure an SMTP server to prevent inbound SMTP connections for domains it doesn't serve. c. Keyword filtering is technically obsolete. d. Blacklists are undependable.

*write a program that defines symbolic names for several string literals (chars between quotes). * use each symbolic name in a variable definition. * use of symbolic to compose the assembly code instruction set can perform vara = (vara - varb) + (varc - vard); ensure that variable is in unsigned integer data type. * you should also further enhance your symbolic logic block to to perform expression by introducing addition substitution rule. vara = (vara+varb) - (varc+vard).