Step 1: Test the Assertion using a boundary value.
If \(p = 5\), then \(P(E) = 0.2 \times 5 = 1\), the largest possible probability, a certain event, so this is still allowed. If p were any bigger than 5, \(P(E)\) would exceed 1, which is impossible for any probability.
Step 2: Confirm the Assertion is true.
So p cannot be more than 5, and Assertion (A) is true.
Step 3: Check the Reason on its own.
Reason (R) states \(P(\overline{E}) = 1 - P(E)\), this is a standard, always-true rule for complementary events, so Reason (R) is also true.
Step 4: Decide if R explains A.
The bound on p came purely from the rule \(P(E) \le 1\), not from the complement rule \(P(\overline{E}) = 1 - P(E)\), so R, though true, does not explain A. This matches option (B).
\[ \boxed{\text{Option (B)}} \]