Terry is building a web site and wants to have three main links called Home, Product Info, and Contact Us$.$ She will create a hierarchy of page elements and revise the style sheets.

$$Terry has decided to display the text of all h$1$ headings found within the page header in green. The style rule applied should be $\_\_\_\_\_.$

a$.$header h$1\{$shade: green;$\}$

b$.$header h$1\{$color: green;$\}$

c$.$header h$1\{$green: shade;$\}$

d$.$header h$1\{$green: color;$\}$