Celtic have dominated the nominees for Scotland's PFA Player of the Year award following their resounding title success this season.
Sinclair was voted Celtic's player of the season by both his teammates and fans following a 25-goal campaign, whereas Armstrong has registered 14 goals since earning a regular starting role in October.
Dembele, meanwhile, has worked his way in front of last year's Scotland player of the year Leigh Griffiths as Celtic's main striker, going on to score 32 goals for the Hoops.
Dembele is also up for the Young Player of the Year award alongside teammates Kieran Tierney and Patrick Roberts, as well as Hibernian striker and Scottish Championship player of the year Jason Cummings.
The winners will be announced on Sunday night at the annual awards dinner in Glasgow.