Final answer:
The degree of X = pvqvr ⇒ (r ⇒ qvr) is the count of all the literals in the expression, which totals to 9. The given options do not contain 9, indicating a possible error in the question or options.
Step-by-step explanation:
The degree of a boolean expression indicates the number of literals present in it. To find the degree of the given expression X = pvqvr ⇒ (r ⇒ qvr), we must count each literal, considering that repeated literals in different terms are counted separately.
Looking at the expression pvqvr, there are two p literals, two q literals, and three r literals. For the part (r ⇒ qvr), we have one r literal, one q literal, and one r literal. Adding these together, we get 2(p) + 3(q) + 4(r) = 9 literals. So, the degree of X is 9. However, this does not match any of the provided answer options, suggesting an error in either the question options or the interpretation of the degree concept.