Classify each element as main-group or transition element.
a. K
b. Ti
c. Zr
d. Cl

• A. K = main-group element; Ti = transition element; Zr = main-group element; Cl = main-group element
• B. K = main-group element; Ti = main-group element; Zr = transition element; Cl = main-group element
• C. K = transition element; Ti = transition element; Zr = transition element; Cl = main-group element
• D. K = main-group element; Ti = transition element; Zr = transition element; Cl = main-group element

Answer: (D)