The display in d1 should read, "colin mccain”.

what text function should be used?

substitute(d1,“c”,”c”)
substitute(d1,“c”,”c”,1)
substitute(d1,“c”,”c”,1)
substitute(d1,“c”,”c”,2)

SUBSTITUTE(D1,“c”,”C”,1)  is the correct answer to be used to display in D1 should read, "Colin McCain”.  

Explanation:

In MS-Excel they are many in bulletin function is available.

SUBSTITUTE is in builtin and is available in ms-excel. The purpose of these function to find a char or string and replace with new string or char on selected cell or range cells.

In this scenario, the end-user likes to replace small letter char “c” with a capital letter  “C”.  

And displays the changes in D1 cells.

SUBSTITUTE has four parameters.

1.Output cell reference

2.What character or string to be found  

3.What to be replaced with character or string if case search character or string founded.

4.from where the search to start from the given length of string

when listing items that have an order of priority.