Use the Information for the Question(s)below

Use the information for the question(s) below.
Suppose the market portfolio's excess return tends to increase by 30% when the economy is strong and decline by 20% when the economy is weak.A type S firm has excess returns that increase by 45% when the economy is strong and decrease by 30% when the economy is weak.A type I firm will also have excess returns of either 45% or -30%,but the type I firm's excess returns will depend only upon firm-specific events and will be completely independent of the state of the economy.
-What is the beta for a type I firm?

A) 1.0
B) 0.75
C) 0.0
D) 1.5