Raising the temperature of a reaction of a secondary alkyl halide with a base increases the proportion of elimination relative to substitution mainly because

1. Aelimination has the higher activation energy and gives more product molecules, so it gains more from a rise in temperature
2. Bsubstitution has the higher activation energy
3. Cthe halide becomes a better nucleophile at high temperature
4. Dthe base becomes weaker at high temperature