Lower temperatures will slow down the activation
Step-by-step explanation:
Yeast has an optimum temperature of around 30-40 degrees Celsius. If the temperature is within this range, the yeast will be activated quickly and so the bread will also rise quickly. Below this temperature, the yeast will either be activated very slowly (bread would rise slowly) or it would not be activated at all (bread would not rise). Above the specified range and the yeast will possibly be denatured/killed, which will mean that the bread will not rise