Yes, of course, as an adjective, 'pedestrian' can very well refer to qualities having to do with walking on foot, as in 'pedestrian pace' as you say-- which, compared to a moving car, is indeed a slow pace, but in itself has no derogatory notion of lacking motivation, or even, moving slowly.
But, as Clive initially points out here, the word also has another frequent use, meaning dull, ordinary, common. I'd be very surprised to learn that it does not have this usage, particularly in critical dialogue, in the UK.
It is actually the first definition in Merriam-Webster.
We don't need to go through any convoluted thinking to arrive at answer (D).