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We discuss the production mechanism of fully charm tetraquark, observedrecently by the LHCb at M = 6.9 GeV in the $J/\psi J/\psi$ channel. Both singleparton scattering (SPS) and double parton scattering (DPS) mechanisms areconsidered. We calculate the distribution in the invariant mass of thefour-quark system $M_{4c}$ for SPS and DPS production of $c c \bar c \bar c$ inthe $k_t$-factorization approach. We present transverse momentum distributionin $p_{t,4c}$ for $c \bar c c \bar c$ system in a mass window around tetraquarkmass. The calculation of the SPS $g^* g^* \to T_{4c}(6900)$ fusion mechanism isperformed in the $k_T$-factorization approach assuming different spin scenarios($0^+$ and $0^-$).

What is the mechanism of the $T_{4c}(6900)$ tetraquark production?