Multi-choice problem: Continue writing the next sentence in this paragraph:

How to check a dog for a fever
Prepare the thermometer.
Lubricate the tip with petroleum jelly or water based lubricant such as " ky jelly. " lubricating the thermometer will make the experience slightly less uncomfortable for your dog.

Select from:
a). Insert the thermometer into the dog's ear cavity. Rotate the thermometer 90 degrees so that it is on the inside of the ear canal.
b). Dip the thermometer into the peanut butter and place a single layer of petroleum jelly on the tip. Alternatively, you could place your thermometer on a skewer instead.
c). If you have a digital thermometer, turn it on and make sure that it is in working order before inserting it into the rectum. Most digital thermometers can read in fahrenheit or celsius.
d). Call your vet if you suspect that your dog may be having a fever. Your vet will decide whether to change the thermometer for you or your dog.
c).