Okay. The tricky thing is the ANO, which imposes a blanket limitation, regardless of the airspace, for any such PPL holder, to a minimum flight viz of 3 km in uncontrolled airspace.
(ANO Schedule 8, Part A, Section 1, Subsection 1, PPL, article 2c.)
If the PPL holder also holds an IR or IMC, then the class F/G minima apply, which range from 1500m to 8km, depending on altitude, as per the UK IAP.
http://www.ais.org.uk/aes/pubs/aip/pdf/enr/20104.PDF
So the only answer that's false in any case is 1500m. The others may all be correct, depending on the altitude: 3km below 3000 feet, 5km between 3000 feet and FL100, and 8km above FL100.