A. Segoe UI is the default font for headings
B. Segoe UI has a more narrow letter spacing
C. Headings allow a lesser number of letters in the headings
D. Smallest heading tag is

Solution

C. Headings allow a lesser number of letters in the headings

Explanation

Segoe UI is the default font for headings. Segoe UI has a more narrow letter spacing. This allows for a few more letters in the headings.