Answer:
C.
is the right answer
Step-by-step explanation:
Let

be the n'th term of the sequence.
so

is the first term,

the second term and so on...
In a geometric sequence with

, and common ratio r, the terms are as follows:




.
.
that is, each term is its previous term times the common ratio r.
In our example

and


so


Answer: r=0.75
5/6 litre of Smoothie = 2/3 cups of smoothie
Divide both sides by 5/6
So 1 litre of smoothie = 2/3 ÷ 5/6 cup of smoothies
= 2/3 × 6/5 cup of smoothies
= 4/5 cup of smoothies