  The observation of multi-particle azimuthal correlations in high-energy
small-system collisions has led to intense debate on its origin and the
possible coexistence from two competing theoretical scenarios: one based on
initial-state intrinsic momentum anisotropy (ISM), and the other based on
final-state collective response to the collision geometry (FSM). To complement
the previous scan of asymmetric collision systems ($p$+Au, $d$+Au and He+Au),
we propose a scan of small symmetric collision systems at RHIC, such as C+C,
O+O, Al+Al and Ar+Ar $\sqrt{s_{\mathrm{NN}}}=0.2$ TeV, to provide further
insights in disentangling contributions from these two scenarios. These
symmetric small systems have the advantage of providing a better controlled
initial geometry dominated by the average shape of the overlap region, as
opposed to fluctuation-driven geometries in asymmetric systems. A transport
model is employed to investigate the expected geometry response in the FSM
scenario. Different trends of elliptic flow with increasing charge particle
multiplicity are observed between symmetric and asymmetric systems, while
triangular flow appears to show a similar behavior. Furthermore, a comparison
of O+O collisions at $\sqrt{s_{\mathrm{NN}}}=0.2$ TeV and at
$\sqrt{s_{\mathrm{NN}}}=2.76-7$ TeV, as proposed at the LHC, provides a unique
opportunity to disentangle the collision geometry effects at nucleon level from
those arising from subnucleon fluctuations.
