Emilio buys pizza for $10 and lemonade for $2. He has income of $100. His budget constraint will experience a parallel outward shift if which of the following events occur?

a The price of pizza falls to $5, the price of lemonade falls to $1, and his income falls to $50 b The price of pizza rises to $20, the price of lemonade rises to $4, and his income remains the same c The price of pizza falls to $8, the price of lemonade falls to $1, and his income rises to $120 d The price of pizza rises to $20, the price of lemonade rises to $4, and his income rises to $400