In the following passage some of the words have been deleted. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.

Comprehension:
Yes, there’s definitely something to be said about (1) ______ the perfect cup of coffee. I’m staring (2) ______ the machine again, but today I’m smiling. I’ve done it - the correct amount of foam, the (3) ______ like silk and the little dusting of chocolate, (4) ______ a perfect heart on the top. It’s just a shame that it’s me who is drinking it, not a/an (5) ______ customer.

Select the most appropriate option to fill in blank number 5.