The answer is C. salire: accelerate
Salire is an Italian Verb that translates as “to ascend” or “to go up”.
Whilst, accelerate is defined as an increase in units such as speed, momentum or any actions being done at the moment.
If raining lunchtime, (I'll remain indoors. )
Or
If it's raining at lunchtime time, (I'll remain indoors.)
(when you know it may rain)
Or
If it rains lunchtime, (I'll remain indoors. )
(when you're not sure it's going to rain)
Hope this helps!