read the slogan.
the window cleaner that makes glass invisible again.
which technique does the writer use to make the slogan memorable?
alliteration
a pithy slogan
word play

The answer is: A pithy slogan.

Explanation:

Let's discard the other options first...

We have: alliteration, and in this slogan it is not used this technique as this term refers to sames sounds or same consonants at the beginning of each word -this is not the case. A word play is mostly known for creating contradictions and/or redundancies -again, this is not the case. And finally a pithy phrase or slogan accordind to this context, means to give a brief but full of meaning phrase, needless to include so many words to let your audience know what you exactly mean, which here, it is the case:

What else could we add? Nothing as it is clear that if you use that product, your windows will be super clean!

a complex sentence consists of an independent clause and one or more dependent clauses.  

to write complex sentences, we must use subordinating conjunctions.  

all the complex sentences begin with a subordinating conjunction and when it occurs, a comma must be place at the end of the dependent clause. on the contrary, if the sentence begins with an independent clause, then no comma is used.

after  

although  

as  

because  

before  

if  

since  

when  

for example,  

after she won the competition, she became very popular.  

although my father was hurt, he continued fighting for his rights.  

as all of you got a ten, you will be able to leave early today.  

before he went to the war, he asked his parents to bless him.  

if it is cold, i won’t go out.  

since you didn’t bring the homework, you will get low grades.  

when it is hot in the town, everyone goes to the beach.  

you know if a word is hiatus if there is a break somewhere in the word