The given word 'tepid' is 'moderately warm or lukewarm'.
From the options, Option B: 'warm' best expresses the meaning of the given word. Hence option B is correct.
Option A: 'Hot' is having a high temperature, higher than 'warm' or 'tepid'.
Option C: 'Cold' is the absence of heat.
Option D: 'Boiling' is when something is so hot that it starts steaming and bubbling.
These words do not mean the same as the given word, hence options A, C and D are incorrect.