When moving from element 10 (neon, a noble gas) to element 11 (sodium, an alkali metal) on the periodic table, the change in reactivity is that element 10 (neon) is inert and does not readily react with other elements, while element 11 (sodium) is very reactive. Therefore, the correct interpretation of the change in reactivity is:
Noble gases are inert. Alkali metals are very reactive.
If you are required to choose from the options, the appropriate statement would be:
Noble gases are inert. Alkali metals are very reactive.