Price elasticity of demand — practice question

The table shows one person’s demand for four goods at two income levels. Across this income range, for which good does that person have an income elasticity of demand = 1?

• Agood A: $1000 -> 50; $1100 -> 50
• Bgood B: $1000 -> 50; $1100 -> 55
• Cgood C: $1000 -> 50; $1100 -> 60
• Dgood D: $1000 -> 50; $1100 -> 100