The question is incomplete:
Complete question is
The most efficient way to determine whether a reaction is an exothermic chemical reaction is to use —
A) an oxygen probe
B) a temperature probe
C) a pressure probe
D) a pH probe
...............................................................................................................
Answer:
Reaction is said to be exothermic in nature, if heat is evolved from the system. The resultant product formed is more stable. Since, during exothermic reaction, heat is given out be the system, temperature of system will increase. Hence, temperature is the probe to determine exothermic reaction.
Thus, correct answer is option B) a temperature probe