There are Type D (5-6 amp, depending on the country's standard) and Type M (15-16 amp) sockets, which would narrow the countries on that list down a bit.
But these sockets look like they're the ones made by Anchor which is a popular brand in India, so probably not any of the other countries on the list.
Types D and M were used in the UK until after WWII, when they came up with their current Type G. Obviously, lots of former British colonies use D, M, and G or some mix of them. Last time I visited India, I saw some newer constructions that had combination sockets that allowed for G even though it's not part of the standard there.
There was an even smaller version of Type D/M rated at 2 amp but I don't think it's in use anywhere nowadays.
Sorry for the useless trivia, I just have a strange fascination