Final answer:
The correct statement to assign the given elements to a tuple is 'a = (42, 56, 7),' using parentheses to create the tuple.
Step-by-step explanation:
The correct statement to assign a tuple containing the elements 42, 56, and 7 to the variable a is:
a = (42, 56, 7)
Options b and c are not valid tuple assignments because they don't use parentheses, and option d assigns a string to the variable a rather than a tuple. In Python, tuples are defined by enclosing the elements within parentheses. Therefore, the correct answer is option a.