Answer:
1. b
2. b
3. a
Step-by-step explanation:
1. You need a vowel in order to add a -s to most words in Spanish so for words that already end in a vowel you just need to add the -s. You would add -es if the word ends in a constant.
2. -ar, -er, and -ir are the three forms words will end in. Each ending has it's own rules for conjucation.
3. Tener ends in -er so in order to conjucate it you would have to remove -er and replace it with the proper word endings.
spanishdict.com is a great resource for learning about conjucation in Spanish!