Standard temperature is exactly
a. 100ºc. b. 273ºc. c. 0ºc. d. 0 k.

  c.  0 °C

Explanation:

Standard temperature is 273.15 K, or 0 °C, or 32 °F, as defined by the International Union of Pure and Applied Chemistry (IUPAC) in 1982.

Standard temperature is exactly (C) 0ºC

Explanation:

STP means standard temperature pressure at which

T = 0℃ or 273K and Pressure = 1 atm

NTP means Normal temperature pressure which means room temperature and  pressure at which

T = 20℃ or 293 K and Pressure = 1 atm

SATP means standard Ambient temperature pressure at which

T = 25℃ or 298K and P = 1atm

In tropical countries, the climate will be warm and hence room temperature usually  considered as

T = 25℃ or 298K and P = 1 atm  

Lab temperature is same as that of room temperature.