Degeneracy between A_lens and log|f_R0| for different observation combinations. Those include CMB temperature and polarization only (blue); CMB temperature, polarization, and lensing (green). The case when A_lens is considered as a systematic effect and is applied only to the primary CMB anisotropies is also shown in magenta. The contours correspond to the 68th and 95th percentiles of the posterior samples.