The traditional land measurement system in Uttar Pradesh follows: 20 Kachwansi = 1 Biswansi, 20 Biswansi = 1 Biswa, and 20 Biswa = 1 Bigha. Therefore, option B claiming '20 Biswansi = 10 Biswa' is incorrect - it should be 20 Biswansi = 1 Biswa. 1 Bigha is approximately 55 x 55 square yards in UP. This question asks which measurement is NOT correct, so B is the right answer because it has the wrong conversion.