Answer:
c. Littler and littlest
Step-by-step explanation:
When using comparative form, the ending -er is used to create the comparative of adjectives and adverbs ending in -y, -le, or -er. Otherwise, you’ll use more to form the comparative.
When using superlative form, the ending -est is used to create the superlative of adjectives and adverbs ending in -y, -le, or -er. Otherwise, you’ll use most to form the superlative.