Albert wants to show that tan(theta)sin(theta)+cos(theta)=sec(theta). He writes the following proof: tan(theta)sin(theta)+cos(theta)=sec(theta) sin(theta)/cos(theta) sin(theta)+cos(theta)=sec(theta) sin^2(theta)/cos(theta)+cos(theta)=sec(theta) What is the next step in this proof? A.) He should write tan(theta)=sin(theta)/cos(theta) to find a common denominator. B.) He should write cos(theta)=cos^2(theta)/cos(theta) to find a common denominator. C.) He should write cos(theta)=1-sin(theta) to convert all the terms to sine. D.) He should write sin(theta)=1-cos(theta) to convert all the terms to cosine.