Le-Chatellier Principle Application

On the basis of Le-Chatellier's principle,
the condition that is unfavourable for
the formation of SO3 is

2SO2(g) + O2(g)-----------> 2SO3(g) ;
ΔH = − 42 kcal

(1) low pressure
(2) high pressure
(3) high temperature
(4) high concentration of SO2

THere can be 2 answers to this question - 1 and 3
But the answer given is only 3....any ideas?