  The quantum numbers of the X(3872) meson are determined to be JPC = 1++ based
on angular correlations in B+ to X(3872) K+ decays, where X(3872) to pi+pi-
J/psi and J/psi to \mu+\mu-. The data correspond to 1.0 fb-1 of pp collisions
collected by the LHCb detector. The only alternative assignment allowed by
previous measurements, JPC=2-+, is rejected with a confidence level equivalent
to more than eight Gaussian standard deviations using the likelihood-ratio test
in the full angular phase space. This result favors exotic explanations of the
X(3872) state.
