Q30

Let r be a relation instance with schema R = (A, B, C, D). We define $r_1 = \pi_{A, B, C} (R)$ and $r_2=\pi_{A, D} (r)$. Let $s =r_1 \: * \: r_2$ where $*$ denotes natural join. Given that the decomposition of $r$ into $r_1$ and $r_2$ is lossy, which one of the following is TRUE?