To store the radius of a circle in a variable, which of the followings is the best option? O a float variable with name b an int variable with name a a float variable with name radius an int variable with name radius Amal declares a variable named _ICt_2013. Identify which of the followings is a true statement. It is a valid variable. It is invalid because it contains the lower case (ie, small) letter t. It is invalid because it starts with a special character underscore (L). It is invalid because it contains a special character underscore ( _) between ICt and 2013