  The progenitors of low-luminosity Type II-Plateau supernovae (SNe II-P) are
believed to be red supergiant (RSG) stars, but there is much disparity in the
literature concerning their mass at core collapse and therefore on the main
sequence. Here, we model the SN radiation arising from the low-energy explosion
of RSG stars of 12, 25, and 27 M$_{\odot}$ on the main sequence and formed
through single star evolution. Despite the narrow range in ejecta kinetic
energy (2.5$-$4.2$\times$10$^{50}$ erg) in our model set, the SN observables
from our three models are significantly distinct, reflecting the differences in
progenitor structure (e.g., surface radius, H-rich envelope mass, He-core
mass). Our higher mass RSG stars give rise to Type II SNe that tend to have
bluer colors at early times, a shorter photospheric phase, and a faster
declining $V$-band light curve (LC) more typical of Type II-linear SNe, in
conflict with the LC plateau observed for low-luminosity SNe II. The complete
fallback of the CO core in the low-energy explosions of our high mass RSG stars
prevents the ejection of any ${}^{56}$Ni (nor any core O or Si), in contrast to
low-luminosity SNe II-P, which eject at least 0.001 M$_{\odot}$ of ${}^{56}$Ni.
In contrast to observations, type II SN models from higher mass RSGs tend to
show an H$\alpha$ absorption that remains broad at late times (due to a larger
velocity at the base of the H-rich envelope). In agreement with the analyses of
pre-explosion photometry, we conclude that low-luminosity SNe II-P likely arise
from low-mass rather than high-mass RSG stars.
