Hey there! posted picture of question

For this case we have the following function:
 f (x) = 5 * (1/3) ^ x
 We must evaluate the function for x = 4
 We have then:
 f (4) = 5 * (1/3) ^ 4
 Rewriting:
 f (4) = 5 * (1/81)
 f (4) = 5/81
 
 The function evaluated at x = 4 is:
 f (4) = 5/81
 option C