How to identify a strong vs weak relationship on ERD?

Question

A dashed line means that the relationship is strong, whereas a solid line means that the relationship is weak. On the following diagram how do we decide that the relationshi

Answer 1

We draw a solid line if and only if we have an ID-dependent relationship; otherwise it would be a dashed line.

Consider a weak but not ID-dependent relationship; We draw a dashed line because it is a weak relationship.